Influence of glucose infusions on luteinizing hormone secretion in the energy-restricted, primiparous, lactating sow.

The objective of this experiment was to evaluate the influence of glucose infusion during lactation on LH secretion in the energy-restricted sow. Ten primiparous Landrace x Yorkshire sows (152 kg postfarrowing) were fed a low-energy (6.5 Mcal of ME/d), high-lysine (45 g/d), corn-soybean meal diet throughout lactation. On d 18 of lactation, sows received a continuous infusion (1 L/12 h) of glucose (50% dextrose solution) or .9% saline from 1200 to 2400. Blood samples were drawn every 15 min for an 18-h period on d 18 to evaluate concentrations of plasma glucose, serum insulin, and serum LH before (600 to 1200) and during (1215 to 2400) the infusions. The glucose infusion immediately increased (P less than .001) plasma glucose and serum insulin relative to preinfusion levels. Glucose and insulin concentrations in sows receiving the glucose infusion were higher (P less than .001) throughout the infusion period relative to concentrations in sows receiving a saline infusion. Glucose infusions had no influence on LH pulsatility during the 12-h infusion period. In contrast to the response observed in the nutrient-restricted gilt, these results indicate that glucose infusions do not result in an immediate increase in pulsatile LH secretion in the energy-restricted, lactating sow.     

Depression of hyperglycemic response to glucagon by parenteral lead administration in sheep.

The insulin and glucose responses to glucagon infusions (27 microgram/hr) were determined in sheep before and after parenteral lead treatment (6 mg/kg intravenously). Glucose production was measured by primed continuous infusion of [6-3H]glucose. Glucagon and insulin concentrations before and during glucagon infusions were not significantly different between lead treatment and control experiments. Lead administration did not affect the concentration or production of glucose in the preinfusion period. However, depressed hyperglycemia during glucagon infusion in lead treated experiments tended to be associated with decreased glucose production. The reduced glucogenic response to glucagon may be the result of reduced function of pyruvate carboxylase, a key hepatic gluconeogenic enzyme in sheep, from lead induced impairment of mitochondrial function.     

不同剂量钼对小尾寒羊组织病理变化及抗氧化功能影响

为了研究不同剂量钼对小尾寒羊病理组织学变化及抗氧化功能的影响,试验选取18只2月龄健康、大小匀称[(20±1.34)kg]小尾寒羊公羊,随机分为3组,因加钼量的多少分为Ⅰ组[60 mg/(kgBW.d)]、Ⅱ组[30 mg/(kgBW.d)]、Ⅲ组[0 mg/(kgBW.d)],每日记录临床表现,定期抽取血液样品,末期采取组织进行研究。结果表明:①两个水平的钼添加剂量下,试验羊均出现典型的钼中毒症状,剂量越高,症状表现越严重;同时,肝脏、脾脏、睾丸、心肌、肾脏均出现不同程度的病理学变化,剂量越高,病理学变化越明显,而肺脏、淋巴结无明显变化。②血清GSH-Px、SOD活性随钼剂量的增加而降低(P<0.05),血清XOD活力和血清MDA浓度随钼剂量的增加而升高(P<0.05),有明显的剂量-效应关系。研究表明,30 mg/(kgBW.d)和60 mg/(kgBW.d)钼能引起小尾寒羊组织损伤和抗氧化机能降低,钼剂量越高,毒性作用越明显。     

Effects of ruminal infusion of volatile fatty acids on plasma concentration of growth hormone and insulin in sheep.

In an initial experiment we observed postprandial changes in plasma concentrations of growth hormone (GH), insulin, glucagon, and somatostatin (SRIF) in sheep. We then examined whether increasing the rumen concentration of volatile fatty acids (VFA) by infusing a VFA mixture at three rates (53.5, 107, and 214 micromol/kg/min for 4 hr) mimicked the postprandial changes in hormone secretion. Feeding significantly (P < 0.05) suppressed the plasma GH concentration for 6 hr, whereas it significantly (P < 0.05) increased plasma concentrations of insulin, glucagon, and SRIF. Plasma glucose levels tended to decrease after feeding but then gradually increased over the prefeeding level (P < 0.05). Intraruminal infusion of the VFA mixture at 107 micromol/kg/min caused similar changes in ruminal VFA concentrations to those seen after feeding. The infusion significantly (P < 0.05) suppressed GH secretion in a dose-dependent manner, whereas it caused a significant (P < 0.05) increase in insulin and glucose concentrations without changing glucagon concentrations. From these results, we conclude that the postprandial change in ruminal VFA concentration may be a physiological signal which modifies GH and insulin secretion in sheep.     

青藏高原高寒草甸土壤N_2O排放通量对温度和湿度的响应

试验采用室内培养的方法研究了青藏高原矮嵩草草甸土壤氧化亚氮(N2O)排放通量对土壤温度和湿度的响应过程。结果表明:随培养温度增加,培养初期矮嵩草草甸土壤N2O排放速率逐渐降低(P0.05),最高排放速率为4.75±0.24g/(kg·h),最低排放速率仅为2.92±0.19g/(kg·h);而经过7d培养,高寒草甸土壤N2O排放速率先降低,而且转变为弱汇,而后升高,30℃时最高,为0.67±0.06g/(kg·h),各处理均显著低于短期培养时排放速率(P0.05);随土壤湿度增加,短期培养矮嵩草草甸土壤N2O排放速率先降低随后升高,在土壤湿度为60%时排放速率最高,为(3.62±0.38)g/(kg·h),而在75%时排放速率最低,为(3.38±0.25)g/(kg·h);随着培养时间延长,高寒草甸土壤N2O排放速率逐渐降低,最高排放速率为(0.55±0.32)g/(kg·h);土壤湿度分别为45%和温度为20℃、以及60%和30℃时,1d和7d培养矮嵩草草甸土壤N2O排放速率最高;而在土壤湿度为45%和30℃、以及75%和30℃时,1d和7d培养矮嵩草草甸土壤N2O排放速率最低,后者呈现吸收现象,吸收速率约为-1.84g/(kg·h)。     

Effect of intravenous infusion of recombinant ovine leptin on feed intake and serum concentrations of GH, LH, insulin, IGF-1, cortisol, and thyroxine in growing prepubertal ewe lambs

In sheep, serum concentrations of leptin change congruently with increases or decreases in nutritional status, while intracerebroventricular infusions of leptin dramatically suppress feed intake in well-fed lambs, and may also increase growth hormone (GH), and/or luteinizing hormone (LH) in undernourished lambs. The objective of the present study was to determine the effects of peripherally delivered ovine leptin, via intravenous infusions, on feed intake and serum concentrations of GH, LH, insulin, IGF-1, cortisol, and thyroxine. Twelve ewe lambs weighing 29.4 +/- 0.7 kg were infused intravenously with a linearly increasing dose of leptin or saline (n = 6 per group) for 10 days, reaching a maximum dose delivered of 0.5mg/h on day 10. Feed intake was assessed twice daily, and blood samples were collected every 10 min for 6 h on days 0, 2, 5, 8, and 10. Serum concentrations of leptin increased in leptin-treated lambs by day 2 (P = 0.05), and continued to increase to concentrations 9-fold greater than saline-infused lambs by day 10 (P < 0.001). Despite the substantial increase in serum leptin, feed intake did not differ between leptin and saline-infused lambs except on day 3.5 (P = 0.01). Furthermore, intravenous infusions of leptin did not significantly influence serum concentrations of insulin, cortisol, IGF-1, thyroxine, LH, or GH. Collectively, these observations contrast with the potent hypophagic effects of leptin when delivered intracerebroventricularly into well-fed lambs. The reasons for the disparate response of lambs treated intravenously with leptin, versus that reported for lambs treated intracerebroventricularly with leptin are not known, but may provide insight into the mechanism(s) of leptin resistance.     

Plasma progesterone concentration in beef heifers receiving exogenous glucose, insulin, or bovine somatotropin

Three experiments were conducted to evaluate plasma concentrations of glucose, insulin, IGF-I, and progesterone (P4) in pubertal beef heifers receiving exogenous glucose, insulin, or sometribove zinc. All heifers used had no luteal P4 synthesis but received a controlled internal drug-releasing device containing 1.38 g of P4 to estimate treatment effects on hepatic P4 degradation. In Exp. 1, 8 pubertal, nulliparous Angus × Hereford heifers (initial BW = 442 ± 14 kg; initial age = 656 ± 7 d) were randomly assigned to receive, in a crossover design containing 2 periods of 10 h, intravenous (i.v.) infusions (10 mL) of insulin (1 μg/kg of BW; INS) or saline (0.9%; SAL). Treatments were administered via jugular venipuncture in 7 applications (0.15 μg insulin/kg BW per application) 45 min apart (from 0 to 270 min). Blood samples were collected immediately before each infusion as well as at -120, -60, 330, 390, and 450 min relative to the first infusion. Heifers receiving INS had greater (P < 0.01) plasma insulin, reduced (P ≤ 0.04) plasma glucose and IGF-I, and similar (P = 0.62) plasma P4 concentrations compared with SAL heifers. In Exp. 2, the same heifers were assigned to receive, in a similar experimental design as Exp. 1, i.v. infusions (10 mL) of 1) insulin (1 μg/kg BW) and glucose (0.5 g/kg BW; INS+G) or 2) SAL. Heifers receiving INS+G had greater (P ≤ 0.02) plasma insulin, glucose, and P4 but reduced (P = 0.01) plasma IGF-I concentrations compared with SAL heifers. In Exp. 3, the same heifers were assigned to receive, in a crossover design containing 2 periods of 14 d, subcutaneous (s.c.) injections of 1) 250 mg of sometribove zinc (BST) or 2) SAL. Blood samples were collected 3 h apart (0900, 1200, 1500, and 1800 h) from heifers on d 6, 8, and 10 relative to treatment administration (d 1). Heifers receiving BST had greater (P < 0.01) plasma glucose and IGF-I and similar (P ≥ 0.67) plasma insulin and P4 concentrations compared with SAL heifers. Results from this series of experiments suggested that concurrent increases in glucose and insulin are required to reduce hepatic catabolism and increase plasma concentrations of P4 in bovine females.     

Heat energy for growing goats and sheep grazing different pastures in the summer.

Angora goat, Spanish goat, and Suffolk x Rambouillet sheep wethers (20 of each type; 30.4+/-.57, 31.3+/-.93, and 32.4+/-1.08 kg BW for Angora goats, Spanish goats, and sheep, respectively) were used to investigate influences of animal type and two grass-based pasture treatments on heat energy during summer grazing (mid-August through September in Oklahoma). The improved pasture treatment consisted of .7-ha paddocks primarily of Old World bluestem and johnsongrass, whereas the native pasture treatment entailed 10.8-ha paddocks dominated by big and little bluestems and indiangrass. Grasses were 95 to 100% of diets for the improved pasture treatment and 71 to 95% for the native pasture treatment; forbs were 2 to 25%, and shrubs were less than 4% of diets for the native pasture treatment. Metabolizable energy intake was similar (P > . 10) between pasture treatments but differed (P <.01) among animal types: 79, 99, and 113 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively; SE 7.1. Heat energy estimated via CO2 entry rate was affected by pasture treatment ( P = .08) and animal type (P < .001): improved pasture treatment 109, 132, and 151 kcal/(kg(.75) BW.d); native pasture treatment 126, 138, and 163 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively. Likewise, daylight grazing time was greater (P = .04) for the native than for the improved pasture treatment and differed (P < .01) among animal types: improved pasture treatment 5.3, 4.7, and 6.7 h; native pasture treatment 6.0, 5.7, and 8.1 h for Angora goats, Spanish goats, and sheep, respectively. In conclusion, heat energy during summer grazing of grass-based paddocks was less for goats than for sheep, and animal type can affect the increase in heat energy as energy intake and grazing time increase.     

Inhibition of endogenous nitric oxide production influences ovine hindlimb metabolism independently of insulin concentrations

The hindlimb arteriovenous difference (AVD) model was used to determine whether 30 mg/ kg of the nitric oxide synthase (NOS) inhibitor L-NGnitroarginine methyl ester (hydrochloride; L-NAME) inhibited ovine NO synthesis and influenced muscle metabolism. Eight Border Leicester x Merino cross lambs (50 to 55 kg BW) were infused with saline (control) or saline containing L-NAME via an indwelling jugular vein catheter in a balanced randomized crossover design with 3 d between treatments. The abdominal aorta and deep femoral vein were catheterized for assessment of AVD of hind limb metabolism. Arterial hematocrit and insulin concentration and both arterial and venous concentrations of nitrate/nitrite (NOx), glucose, lactate, NEFA, and urea were determined. Infusion of L-NAME decreased arterial NOx concentrations (P = 0.049), indicating inhibition of systemic NO synthesis. Treatment had no effect on arterial (3.5 vs. 3.6 +/- 0.19 mmol/L for control and L-NAME lambs, respectively; P = 0.39) or venous (3.3 vs. 3.4 +/- 0.16 mmol/L, P = 0.55) plasma glucose concentrations or on glucose AVD (0.19 vs. 0.27 +/- 0.065 mmol/L, P = 0.20). There was an interaction (P = 0.038) between time and treatment, such that L-NAME initially increased the AVD of glucose (up to 180 m) divergent from control lambs. The response was then decreased before a possible inflection beyond 240 min. Infusion of L-NAME increased hindlimb venous NEFA (222 vs. 272 +/- 13.2 micromol/L, P = 0.007) and NEFA AVD (79.4 vs. -13.3 +/- 31.5 micromol/L, P = 0.018). These metabolic changes were independent of plasma insulin concentrations, which were not affected by L-NAME infusion (25.3 vs. 27.8 +/- 3.62 mU/L, P = 0.85). The increase in hindlimb lipolysis after L-NAME infusion does not seem to be due to increased lipolysis of plasma triacylglycerol because circulating arterial (155 vs. 142 +/- 20.8 micromol/L, P = 0.58), venous (154 vs. 140 +/- 20.5 micromol/L, P = 0.50), and AVD (1.0 vs. 2.9 +/- 3.17 micromol/L, P = 0.38) triacylglycerol concentrations were unaffected by L-NAME infusion. In conclusion, these data indicate that infusion of 30 mg of L-NAME/kg inhibits NO synthesis, which in turn influences fat and carbohydrate metabolism in the ovine hindlimb independently of plasma insulin concentrations.     

Effects of nitric oxide donor and nitric oxide synthase inhibitor on ruminal contractions in conscious sheep

The present study was planned to evaluate a role of nitric oxide (NO) in the regulation of regular ruminal contractions in conscious sheep. Intravenous infusion of S-nitroso-acetyl-DL-penicillamine (SNAP) at doses of 3-30 nmol kg(-1) min(-1)for 30 minutes inhibited both the amplitude and frequency of ruminal contractions in a dose-dependent manner. However, intravenous infusion of Nomega-nitro-L-arginine-methyl ester (L-NAME) at doses of 0.3-3.0 micromol kg(-1) min(-1)did not alter the basal tone of intraruminal pressure and the amplitude of ruminal contractions. The frequency of contractions was slightly inhibited by L-NAME infusion at 1.0 micromol kg(-1)min(-1). The effects of L-NAME were abolished by simultaneous infusion of L -arginine at 30 micromol kg(-1) min(-1). These results suggest that exogenous NO can diminish the ruminal contractions, while endogenous NO is not involved in the regulatory mechanism of basal tone and regular phasic contractions of the rumen in healthy sheep.     

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep

Background: The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short(2-wk) and long(8-wk) durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations. We also used direct fetal insulin infusions(1-wk hyperinsulinemic-isoglycemic clamp) to determine the relative importance of fetal glucose and insulin for regulating non-glucose carbohydrates.Results: A maternal insulin infusion resulted in lower maternal(50%, P < 0.01) and fetal(35-45%, P < 0.01) mannose concentrations, which were highly correlated(r2= 0.69, P < 0.01). A fetal insulin infusion resulted in a 50% reduction of fetal mannose(P < 0.05). Neither maternal nor fetal plasma inositol changed with exogenous insulin infusions.Additionally, maternal insulin infusion resulted in lower fetal sorbitol and fructose(P < 0.01).Conclusions: Chronically decreased glucose supply to the fetus as well as fetal hyperinsulinemia both reduce fetal non-glucose carbohydrates. Given the role of these carbohydrates in protein glycosylation and lipid production, more research on their metabolism in pregnancies complicated by abnormal glucose metabolism is clearly warranted.     

三七总皂苷亚慢性毒性试验研究

[目的]评价三七总皂苷(PNS)用药安全性,为临床用药提供参考依据。[方法]将40只昆明系小白鼠随机分为4组,每组10只,3个药物处理组小鼠通过腹腔注射的方式分别给予11.34、56.70、113.40mg/(kg·BW)的PNS,每天1次,连续给药14d;空白对照组小鼠腹腔注射生理盐水0.3mL/只,连续注射14d。测定并比较各组小鼠在试验期间的体重、脏器指数(肝脏、脾脏、肾脏指数)以及血液生化指标;取各组小鼠肝脏、脾脏、肾脏组织,制备病理组织切片,利用显微镜观察上述组织是否出现病理变化。[结果]3个PNS给药组小鼠在试验期间的体重与空白对照组小鼠相比,均无显著性差异(P>0.05);11.34mg/(kg·BW)PNS组小鼠的脾脏指数显著低于空白对照组(P<0.05);113.40mg/(kg·BW)PNS组小鼠的谷草转氨酶活力和肌酐含量显著低于空白对照组(P<0.05),而尿素氮含量显著升高(P<0.05);病理组织学观察结果表明,PNS对肝脏、脾脏、肾脏组织无明显损伤。[结论]PNS实际无毒,长期用药会产生肾毒性,提示用药不宜过量。     

妊娠后期营养限制对蒙古绵羊胎儿生物原胺类神经递质的影响

本试验旨在研究妊娠后期营养限制对蒙古绵羊胎儿生物原胺类神经递质的影响。选择健康、体况相近的蒙古绵羊18只,对其进行同期发情、配种后,从妊娠第90天开始,随机分为3个组:营养限制1组[NG1组,n=6,代谢能(ME)=0.175 MJ/(kg BW 0.75·d)]、营养限制2组[NG2组,n=6,ME=0.330 MJ/(kg BW 0.75·d)]和对照组[CG组,n=6,ME=0.670 MJ/(kg BW 0.75·d)],在妊娠第140天时屠宰,取各组胎儿及其脑组织和血液。结果显示:NG1组胎儿的脑重较CG组显著增高(P<0.05),并且NG1组胎儿脑中5-羟色胺(5-HT)(P<0.01)、肾上腺素(EPI)(P<0.05)含量显著或极显著高于CG组,去甲肾上腺素(NA)的含量极显著低于CG组(P<0.01)。NG2组胎儿脑中5-HT含量极显著高于CG组(P<0.01),而NA(P<0.01)、多巴胺(DA)(P<0.05)含量显著或极显著低于CG组。另外,NG1组胎儿血浆中5-HT(P<0.01)、EPI(P<0.01)、NA(P<0.05)、DA(P<0.01)含量显著或极显著低于CG组;NG2组胎儿血浆中5-HT(P<0.01)、NA(P<0.01)、DA(P<0.05)含量显著或极显著低于CG组。由此得出,妊娠后期营养限制使得蒙古绵羊胎儿脑中5-HT、EPI含量升高和NA含量降低,血浆中5-HT、EPI、NA、DA含量降低。     

Porcine somatotropin alters insulin response in growing pigs by reducing insulin sensitivity rather than changing responsiveness

Exogenous porcine somatotropin (pST) treatment consistently improves growth performance and reduces fat deposition in pigs, and it is hypothesized that one component of the mechanism is through altering the sensitivity and/or responsiveness to insulin. Therefore, a study was conducted to investigate the effect of pST treatment on whole-body glucose metabolism in response to varying doses of insulin. Eight barrows were surgically prepared with indwelling catheters and randomly assigned to one of two treatment groups (0 or 120 μg pST/kg BW · d) for 13 d. Whole-body glucose kinetics were measured during infusion of [6-(3)H]-glucose under basal conditions and during hyperinsulinemic-euglycemic clamps at various insulin infusion rates (7, 28, and 140, and 14, 70, and 280 ng insulin/kg BW · min) and alterations in the dose-response parameters were calculated with nonlinear regression. Treatment with pST increased basal plasma concentrations of glucose (36%; P = 0.005), insulin (276%; P = 0.001), and NEFAs (177%; P = 0.01) and decreased the rate of glucose disappearance (-59%; P = 0.001). The responsiveness (maximum response) for steady state glucose infusion rate to maintain glycemia was not altered by pST (112 vs 106 μmol/min · kg; P = 0.78), whereas the sensitivity (effective dose at 50% of maximum response) was increased almost 7-fold (1.3 vs 8.7 ng/mL; P = 0.027). Similar responses were observed for rate of glucose disappearance and insulin-dependent glucose utilization. Therefore, pST-induced insulin resistance with regard to whole-body glucose uptake is due to a reduced sensitivity to insulin, rather than a change in responsiveness.     

Feedlot efficiency implications on greenhouse gas emissions and sustainability

The term sustainable has many meanings, but in agriculture it generally refers to some balance between environmental, social, and economic goals. The objective of this project was to quantify inputs and outputs to assess the sustainability implications of 2 feedlot cattle management systems: Never Ever 3 (NE3) and a conventional (CON) system using metabolic modifiers. Angus-cross steers (n=104) were stratified by BW (337 kg ± 17) and randomly assigned to 4 pens per treatment group. The NE3 cattle received no feed additives or implants, whereas CON were implanted with 100 mg of trenbolone acetate and 14 mg of estradiol benzoate on d 1 and 70, and were additionally fed monensin [330 mg/(animal·d)] and tylosin phosphate [90 mg/(animal·d)] in their ration throughout the course of the study, and ractopamine hydrochloride at 254 mg/(animal·d) for the last 29 d on feed. Cattle were shipped on a constant average pen weight basis (596 kg ± 32 BW). The CON cattle had greater ADG (1.81 vs. 1.35 kg, P < 0.01) and were on feed fewer days (146 vs. 188 d, P < 0.01) than the NE3 cattle. No significant differences were observed in HCW (P = 0.072) or dressing percentage (P=0.62) between treatments (P > 0.05); however, CON carcasses averaged larger ribeye area (87 vs. 80 cm(2), P < 0.01), greater Warner-Bratzler shear force measurement (WBSF; 3.46 vs. 3.19 kg, P < 0.01), and smaller USDA marbling score (5.4 vs. 6.2, P < 0.01), and less backfat thickness (1.64 vs. 1.84 cm, P < 0.05) and yield grade (3.38 vs. 3.95, P < 0.01) than NE3 carcasses. Overall, CON cattle consumed 393 kg less DM in the feedlot (1,250 vs. 1,643 kg; P < 0.05). No treatment effects were observed for daily methane (CH(4); P=0.62) or nitrous oxide (N(2)O; P=0.7) emissions per steer. Assuming a constant emission rate on a DMI basis throughout the course of the feedlot trial, CON feedlot management resulted in a 31% decrease in emissions per finished steer compared with NE3 management. Expressing CH(4) emissions on a carbon dioxide equivalent (CO(2)-eq) basis revealed a 1.10-kg CO(2)-eq difference per kilogram BW gain (5.02 kg of NE3 vs. 3.92 kg of CON) between the 2 feedlot management systems. Although the metabolic modifiers resulted in additional costs for the CON treatment group, the cost per kilogram of feedlot BW gain was significantly less ($1.12/kg vs. $1.35/kg; P < 0.05) than NE3. Both production systems satisfied some sustainability criteria, although neither concurrently fulfilled all of the environmental, social, and economic goals of agricultural sustainability.     

Renal function studies in normal and toxemic pregnant sheep

Renal blood and plasma flow, glomerular filtration rate (GFR) and maximal tubular transport of PAH (TmPAH) were measured in nonpregnant and twin-pregnant sheep. Twin-pregnant animals were studied during normal pregnancy as well as during ovine pregnancy toxemia artificially produced by starvation. All animals were surgically prepared with aortic, post caval and renal vein cannulas at least one week prior to experimentation. Total renal blood and plasma flow was found to be elevated during pregnancy, but if expressed on the basis of body weight no changes were noted. Starvation and the resultant development of hypoglycemia and hyperketonemia caused a 25-30% decline in renal blood and plasma flow. GFR in pregnant fed sheep (193 ml/min or 2.7 ml/kg.min) was significantly higher (P less than .001) than that of nonpregnant ewes (118 or 2.3 ml/kg min). During ovine pregnancy toxemia the GFR was significantly (P less than .001) diminished (142 ml/min or 2.0 ml/kg min). TmPAH also was significantly higher (179 mg/min or 2.5 mg/kg min) in pregnant animals when compared to nonpregnant ewes (98 mg/min or 1.9 mg/kg min.), but starvation had no effect on Tm PAH in pregnant sheep. It thus appears that a functional renal hypertrophy occurs during pregnancy which is similar to that which follows unilateral nephrectomy or renal disease. During ovine pregnancy toxemia the diminution of renal function probably results from the metabolic derangements and is thus not comparable to human preeclampsia.     

A clinical comparison of remifentanil or alfentanil in propofol-anesthetized cats undergoing ovariohysterectomy

Sixteen cats were used to compare the cardiovascular and anesthetic effects of remifentanil (REMI) or alfentanil (ALF) in propofol-anesthetized cats undergoing ovariohysterectomy. After premedication with acepromazine, anesthesia was induced and maintained with a constant rate infusion of propofol (0.3 mg/kg/min). REMI or ALF infusions were administered simultaneously with propofol. Heart rate (HR), systolic arterial pressure (SAP), pulse oximetry (SpO(2)), rectal temperature (RT), and response to surgical stimulation were recorded at predefined time points during anesthesia. Data [mean±standard deviation (SD)] were analyzed by analysis of variance (ANOVA) for repeated measures followed by a Dunnett's test and Student t-test (P<0.05). SAP was significantly lower in ALF group than in REMI group. Extubation time was significantly shorter in REMI than in ALF group. Overall infusion rate of REMI and ALF was 0.24±0.05 μg/kg/min and 0.97±0.22 μg/kg/min, respectively. The combination of propofol and REMI or ALF provided satisfactory anesthesia in cats undergoing ovariohysterectomy.     

Renal blood flow in hypercholesterolemic pigs is increased by chronic antioxidant treatment

Oxygen radical species can influence vascular tone, and antioxidants may have hemodynamic and vascular effects. To date, the vascular effects of chronic intervention with a combination of antioxidant vitamins E and C on renal blood flow (RBF) in hypercholesterolemia (which increases oxidative stress) have not been fully defined. The aim of this intervention study was to explore the involvement of increased oxidative stress in pig RBF disturbance by using chronic dietary antioxidant vitamin intervention. Responses of RBF to the acetylcholine (Ach) were measured in vivo using electron beam computed tomography (EBCT). Acetylcholine significantly increased RBF in normal and hypercholesterolemic + vitamins (P < 0.05 for both), but not in hypercholesterolemic pigs (P=0.1). In normocholesterolemic + vitamins pigs, Ach infusion did not induce any further increase in RBF, but RBF was similar to that observed in normal and hypercholesterolemic + vitamins under the same conditions, and tended to be higher than in hypercholesterolemic pigs (P=0.06). Thus, antioxidants improve RBF in hypercholesterolemic pigs and this effect may help to prevent renal diseases and hypertension in animals.     

Coordinate regulation of ovine adipose tissue gene expression by propionate

The current study examined the acute effects of intravenous propionate infusion on plasma hormones and metabolites and the expression of adipose tissue lipogenic genes. Four yearling rams were assigned to one oftwo groups (saline or propionate infusion) in a crossover design. All sheep were cannulated in both jugular veins and infused with 1.2 M propionate at a rate of 64 micromol x mix(-1) x kg BW(-1) for 30 min. Blood samples were collected at -10, 0, 5, 10, 20, 30, 60, and 120 min after initiation of infusion. Subcutaneous adipose tissue biopsies were obtained from the tailhead at 0 and 2 h after propionate infusion and analyzed for gene expressions of lipoprotein lipase, acetyl CoA carboxylase, fatty acid synthase, peroxisome proliferator-activated receptor gamma, leptin, and uncoupling protein-2 using a nonisotopic ribonuclease protection assay. The partial cDNA of the enoyl reductase region of ovine fatty acid synthase was cloned and sequenced from s.c. adipose tissue of sheep. The deduced amino acid sequence (210 amino acids) was 86% identical to human, 88% identical to rat, 88% identical to mouse, and 72% identical to chicken. Plasma glucose and insulin concentrations abruptly increased 5 min after beginning propionate infusion and further increased up until 30 min but were unaffected in saline-infused sheep (P < 0.05). Plasma concentration of NEFA decreased (P < 0.05) during propionate infusion, whereas IGF-I levels were unaltered. The amounts of lipoprotein lipase, acetyl CoA carboxylase, fatty acid synthase, peroxisome proliferator-activated receptor gamma, and leptin mRNA increased (P < 0.05) in s.c. adipose tissue of propionate-infused sheep compared with those of saline-infused sheep. However, uncoupling protein-2 mRNA decreased (P < 0.05) in propionate-infused sheep. This study demonstrates that an acute nutrient challenge, in the form of i.v. propionate, can stimulate or inhibit the expression of various adipose tissue genes involved with lipogenesis and adipose tissue metabolism.