蛙心体外循环系统及刺激豚鼠回肠检测外啡肽生物学活性的相关性研究

采用离体蛙心灌流和离体回肠灌流的方法将小麦面筋蛋白胃蛋白酶酶解液分别加入蛙心体外循环系统和豚鼠回肠体外循环系统中,通过BL-420生物机能实验系统测定蛙心心肌和肠道平滑肌收缩力变化,并随即加入特异性阿片肽阻断剂——纳洛酮,以检测小麦面筋蛋白胃蛋白酶酶解液的生物学活性,并将两种方法所得的实验结果经处理后进行相关性比较研究。结果表明,小麦面筋蛋白胃蛋白酶酶解液能显著引起蛙心心肌和肠道平滑肌收缩力加强,并可被纳洛酮逆转此现象,说明小麦面筋蛋白胃蛋白酶酶解液含有外啡肽,对两种方法具有显著的相关性,表明用蛙心灌流法测定外啡肽活性与经典的豚鼠回肠法测定结果是一致的,但蛙心灌流法更易推广。     

Strontium accumulation by sarcoplasmic reticulum and mitochondria in vascular smooth muscle

Electron-opaque deposits of strontium were observed in the sarcoplasmic reticulum and in mitochondria of spontaneously contracting vascular smooth muscles that had been incubated in a strontium-containing solution prior to fixation. The deposits were present in those elements of the sarcoplasmic reticulum that are in close contact with the surface membrane and also in more centrally located portions. In vascular smooth muscle that does not contract spontaneously, similar deposits of strontium were only seen if the muscle was depolarized during or glycerinated before exposure to the strontium-containing solution. Strontium was also deposited in the sarcoplasmic reticulum of the endothelium. It is suggested that translocation of calcium from the sarcoplasmic reticulum that is in close contact with the surface membrane, and now shown to accumulate divalent cations, is responsible for the action potential-triggered contractions of rabbit and guinea pig mesenteric veins. Strontium may also be a suitable marker for identifying sites that accumulate calcium in other types of cells in which translocation of calcium plays a major regulatory function.     

Hypoxic dilation of coronary arteries is mediated by ATP-sensitive potassium channels

The function of the heart depends critically on an adequate oxygen supply through the coronary arteries. Coronary arteries dilate when the intravascular oxygen tension decreases. Hypoxic vasodilation in isolated, perfused guinea pig hearts can be prevented by glibenclamide, a blocker of adenosine triphosphate (ATP)-sensitive potassium channels, and can be mimicked by cromakalim, which opens ATP-sensitive potassium channels. Opening of potassium channels in coronary smooth muscle cells and the subsequent drop in intracellular calcium is probably the major cause of hypoxic and ischemic vasodilation in the mammalian heart.     

Anaphylatoxin release from the third component of human complement by hydroxylamine

Treatment of highly purified preparations of the third component of complement (C3) with 0.5M hydroxylamine at 20 degrees C for 15 to 30 minutes, followed by acidification, resulted in dissociation of a peptide from the C3 molecule. The isolated fragment (molecular weight, 7600) resembled enzymatically liberated anaphylatoxin (C3a) with respect to size, charge, amino acid composition, and biological activity. Its capacity to contract smooth muscle was inhibitable by antihistamines; it also produced tachyphylaxis and desensitization of the guinea pig ileum to C3a. Thus native C3 probably contains an esterlike bond and hydroxylamine-liberated anaphylatoxin may represent one of the polypeptide chains of the C3 molecule.     

ACETYLCHOLINE-LIKE ACTIVITY IN SCIATIC NERVE

Extracts of sciatic nerve exhibit acetylcholine-like activity that is only partly attributable to acetylcholine. The extracts show relatively greater activity on the rectus abdominis muscle of the frog than on the ileum of the guinea pig. To prevent the action of the extract on the frog rectus abdominis muscle, a greater concentration of d-tubocurarine is required than is necessary to prevent the action of known acetylcholine.     

Relaxation of isolated gastric smooth muscle cells by vasoactive intestinal peptide

Vasoactive intestinal peptide caused a prompt, dose-dependent relaxation of isolated gastric smooth muscle cells of the guinea pig and a significant increase in intracellular adenosine 3',5'-monophosphate coincidentally with optimum relaxation. Relaxation was augmented by a threshold concentration of isobutyl methylxanthine. The direct relaxant effect of vasoactive intestinal peptide and the distribution of nerves containing this peptide to circular smooth muscle support the view that vasoactive intestinal peptide is the neuromuscular transmitter of enteric inhibitory nerves.     

Cholinergic action of homogenates of sea urchin pedicellariae

A dialyzable, acetylcholine-like material exists in homogenates of globiferous pedicellariae of the sea urchin Lytechinus variegatus. Its pharmacological characterization was obtained on the basis of the responses of the guinea pig ileum, the rat uterus, blood pressure in the dog, the amphibian heart, the longitudinal muscle of the holothurian, and the protractor muscle of the sea urchin lantern. Some of the data were statistically treated, and an attempt was made to determine a ratio of potency between the homogenates and acetylcholine.     

Chemotactic and anaphylatoxic fragment cleaved from the fifth component of guinea pig complement

The fifth component of guinea pig complement, with a sedimentation coefficient 7.8S, is cleaved by sensitized sheep erythrocytes treated with the first four components of complement into two fragments with sedimentation coefficients of 7.4S and 1.5S. The smaller fragment, with a molecular weight of about 15,000, possesses chemotactic activity for rabbit polymorphonuclear leukocytes, as well as anaphylatoxic activity for guinea pig ileum.     

Vasoactive intestinal peptide: a possible transmitter of nonadrenergic relaxation of guinea pig airways

Vasoactive intestinal peptide, a smooth-muscle relaxant neuropeptide with neurotransmitter properties, was relaxed during electrical field stimulation of guinea pig trachea. The amount released correlated with the degree of relaxation, and the release was blocked by tetrodotoxin. Prior incubation of the trachea with antiserum to vasoactive intestinal peptide reduced the relaxation. Thus vasoactive intestinal peptide may mediate the nonadrenergic relaxation of tracheal smooth muscle.     

镧对大白鼠离体回肠运动的影响

采用37℃恒温平滑肌槽灌流法,通过BL-410生物机能实验系统观察并记录氯化镧、氯化钙、阿托品、酚妥拉明对大鼠离体回肠运动的影响。结果表明:稀土La对大鼠离体回肠运动有明显的抑制作用;在回肠平滑肌细胞外液中,La3+和Ca2+之间存在竞争性拮抗作用;La3+可减少Ca2+内流,使平滑肌兴奋-收缩耦联机制减弱,导致收缩振幅减小;同时La3+,使平滑肌的基本电节律变慢,导致收缩频率减小;La对回肠运动的抑制作用可能与回肠平滑肌上的胆碱能M受体和肾上腺素能α受体都无关。     

Calcium antagonist receptors in cardiomyopathic hamster: selective increases in heart, muscle, brain

The Syrian cardiomyopathic hamster has a hereditary disease in which a progressive myocardial necrosis mimics human forms of cardiac hypertrophy. Lesions are associated with calcium overload and can be prevented with the calcium antagonist verapamil. Numbers of receptor binding sites for calcium antagonists in heart, brain, skeletal muscle, and smooth muscle were markedly increased in cardiomyopathic hamsters. The uptake of calcium-45 into brain synaptosomes was also increased in cardiomyopathic hamsters. The increase in calcium antagonist receptors and related voltage-sensitive calcium channels may be involved in the pathogenesis of this cardiomyopathy.     

Axonal transport: each major rate component reflects the movement of distinct macromolecular complexes

The proteins of the three major rate components of axonal transport in guinea pig retinal ganglion cells were analyzed by one- and two-dimensional gel electrophoresis. Each rate component consisted of a different set of proteins that remained associated with each other during transport. This suggests that each rate component represents a distinct macromolecular complex and that these complexes may be definable organelles such as microtubules, microfilaments, and smooth endoplasmic reticulum. Thus, the transport of radiolabeled proteins in the axon reflects the movement of complete subcellular rather than the movement of individual proteins.     

Spatially resolved calcium dynamics of mammalian Purkinje cells in cerebellar slice

Microfluorometric imaging was used to study the correlation of intracellular calcium concentration with voltage-dependent electrical activity in guinea pig cerebellar Purkinje cells. The spatiotemporal dynamics of intracellular calcium concentration are demonstrated during spontaneous and evoked activity. The results are in agreement with hypotheses of dendritic segregation of calcium conductances suggested by electrophysiological experiments. These in vitro slice fluorescence imaging methods are applicable to a wide range of problems in central nervous system biochemical and electrophysiological functions.     

Atrotoxin: a specific agonist for calcium currents in heart

A specific label for voltage-dependent calcium channels is essential for the isolation and purification of the membrane protein that constitutes the calcium channel and for a better understanding of its function. A fraction of Crotalus atrox that increases voltage-dependent calcium currents in single, dispersed guinea pig ventricular cells was isolated. In the doses used, neither sodium nor potassium currents were changed. The fraction was active in the absence of detectable phospholipase or protease activity, and the active component, designated atrotoxin, produced its effect rapidly and reversibly. The effect was produced by extracellular but not intracellular application of the agent. The increase in Ca2+ current was blocked by the Ca2+ channel blockers cobalt and nitrendipine. The active fraction completely blocked specific [3H]nitrendipine binding to guinea pig ventricular membrane preparations. The inhibition of nitrendipine binding by atrotoxin was apparently via an allosteric mechanism. Thus atrotoxin was shown to bind to the Ca2+ channel and to act as a specific Ca2+ channel agonist.     

Morphiceptin (NH4-tyr-pro-phe-pro-COHN2): a potent and specific agonist for morphine (mu) receptors

The synthetic peptide NH2-Tyr-Pro-Phe-Pro-CONH2 (morphiceptin), which is the amide of a fragment of the milk protein beta-casein, has morphinelike activities and is highly specific for morphine (mu) receptors but not for enkephalin (delta) receptors. It is as active as morphine in the guinea pig ileum but much less active in the mouse and rat vas deferens. The discovery of this specific morphine receptor ligand substantiates the hypothesis of multiple opiate receptors. The ligand, which may be of physiological significance since a very similar, or identical, activity can be detected in enzymatic digests of beta-casein, may prove useful for further investigation of the functions of opiate receptor subtypes.     

Electrocardiographic and behavioral effects of emetine

The effects of subacute emetine poisoning on conditioning, spontaneous behavior, and the electrocardiogram of the guinea pig are reported and compared. The depression in spontaneous behavior shown by the animals does not seem to be dependent upon any psychogenic action of emetine; there appears to be a correlation between the cardiac damage and the depression caused by the drug.     

Relaxation of isolated ventricular cardiomyocytes by a voltage-dependent process

Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.     

Regional changes in calcium underlying contraction of single smooth muscle cells

The role of calcium in regulating the contractile state of smooth muscle has been investigated by measuring calcium and contraction in single smooth muscle cells with the calcium-sensitive dye fura-2 and the digital imaging microscope. The concentration of free calcium in the cytoplasm increased after stimulation of the cells by depolarization with high potassium or by application of carbachol. Changes in calcium always preceded contraction. The increase in calcium induced by these stimuli was limited to less than 1 microM. Calcium within the nucleus was also subject to a limitation of its rise during contraction. Intranuclear calcium rose from 200 nM at rest to no more than 300 nM while cytoplasmic calcium rose to over 700 nM. These apparent ceilings for both cytoplasmic and intranuclear calcium may result either from negative feedback of calcium on cytoplasmic and nuclear calcium channel gating mechanisms, respectively, or from the presence of calcium pumps that are strongly activated at the calcium ceilings.     

松辽黑猪×野猪杂交猪H-FABP mRNA基因的组织分布研究

1材料与方法 1．1材料松辽黑猪X野猪杂交猪（含野猪血缘50％）组织样品采自吉林省农业科学院畜牧分院,采集的皮下脂肪、腹脂、乳腺、背最长肌、臂三头肌、心脏、肝脏、脾脏、肺脏、肾脏、回肠、十二指肠共计12种组织样品迅速置于液氮中,实验室-80℃保存。     

Physalaemin: an amphibian tachykinin in human lung small-cell carcinoma

Immunoreactivity to the amphibian peptide physalaemin was characterized from extracts of a human lung small-cell carcinoma by immunological, chemical, and pharmacological means. Tumor-related peptide cross-reacted with three antiserums to physalaemin to yield 1.1 to 1.6 nanomoles per gram of tissue. Physalaemin and tumor peptide had similar retention times on high-performance liquid chromatography after chemical and enzymic modifications that included pH changes, oxone oxidation, use of a hydrophilic ion-pairing reagent, and digestion with trypsin and pyroglutamate aminopeptidase. Both physalaemin and the tumor peptide produced a contractile response of isolated guinea pig ileum at threshold concentrations of approximately 100 to 150 picograms per milliliter. These data suggest that small-cell carcinoma of the lung contains a physalaemin-like peptide that has structural and biological homology to its amphibian counterpart.