Visceral receptors and their afferents in the caudal mesenteric nerve of the duck

1. The behaviour and reactivities of visceral receptors to different mechanical and chemical stimuli in single unit preparations from the caudal mesenteric nerve of adult ducks were studied to examine the physiological roles of such receptors.

2. In total, 83 single unit activities were recorded from the caudal mesenteric nerve.

3. Receptors were grouped according to their locations in different layers of the rectum as (i) over the branching points of the blood vessel or in the serosal layer, (ii) in the muscle layer or (iii) in the mucous membrane of the rectum.

4. All the receptors, both spontaneous and non‐spontaneous, responded to mechanical probing. Receptors of the muscle layer responded to distension also and showed a slowly‐adapting nature. Most of the receptors of the other two groups were of the rapidly‐adapting type.

5. Conduction velocity ranged from 0.76 to 34.6 m/s.

6. Sympathetic afferent fibres from the hind gut ascend along the intestinal nerve and join the caudal mesenteric nerve via the colonic ganglion.     

Toxico‐kinetics,recovery efficiency and microsomal changes following administration of deltamethrin to black Bengal goats

A study of the toxico‐kinetics, recovery percentage from different substrates, cytotoxicity and role of cytochrome P₄₅₀ and b₅ of liver microsome in the metabolism of deltamethrin were carried out in female black Bengal goat. The ALD₅₀ value of deltamethrin in goat by intravenous route lies between 0.2 and 0.6 mg kg^?1. Intravenous disposition kinetics using a dose of 0.2 mg kg^?1 showed that the maximum blood concentration of deltamethrin was recorded at 0.5 min, followed by rapid decline, and a minimum concentration was detected at 6 min after administration. The following values were obtained : Vd_area 0.148 (± 0.02) litre kg^?1; t_1/2 (α) 0.22 (± 0.02) min; t_1/2 (β) 2.17 (± 0.37) min; K_el 1.05 (± 0.24) min^?1; AUC 4.30(± 0.45) µg min ml^?1; Cl_B 0.05 (± 0.006) litre kg^?1 min^?1; T～B 1.93 (± 0.58); fc 0.40(± 0.05). After 10 min, liver retained the maximum residue, and heart, adrenal gland, kidney, spleen, fat and brain also held the insecticide; liver, fat, heart and spleen retained residue after 30 min, and bone, liver and fat retained residue after 60 min of intravenous administration. Oral absorption of deltamethrin was poor and inconsistent, and approximately 65% of administered dose was recovered from faeces and gastrointestinal contents. The excretion of deltamethrin through urine was meagre, and only 0.01 and 0.013% of the administered dose was recovered after 3 and 5 days of oral administration respectively. All the tissues retained the residue after 3 days; while fat, rumen, reticulum, omasum, abomasum, large and small intestine and bone retained the residue after 5 days of oral administration; and the percentage recoveries were 1.73 and 0.027 respectively. Deltamethrin reduced the level of cytochrome P₄₅₀ content of liver microsomal pellet of goat after 5 days of oral administration. Histopathological examination of liver, kidney, heart, spleen brain and lung sections of treated goats did not reveal any pathological changes. © 2001 Society of Chemical Industry     

Sensory receptors and their afferents in the caudal sympathetic nerve of the domestic duck

1. The behavioural reactivity of the visceral receptors and their afferents in the caudal sympathetic nerve (part of synsacral sympathetic chain) of domestic duck (Anas platyrhynchos) was studied using electrophysiological techniques to examine their involvement in different physiological functions.

2. In total, 114 single unit activities were recorded from the caudal sympathetic nerve of duck.

3. Receptors were classified according to location: in the anal sphincter (32 units), in the mucous membrane of the cloaca (45 units), at the branching point of the blood vessels over the rectum and adjacent mesentery (10 units), at the base of the feather follicles in and around the vent (17 units), and in the ventral and lateral lower abdominal wall muscle (10 units).

4. Both spontaneous and non‐spontaneous receptors responded to mechanical stimuli; average frequency of discharge of non‐spontaneous units being much higher.

5. Most of these receptors were of the rapidly‐adapting type. Only some receptors in the abdominal muscle layer, anal sphincter and mucous membrane of hind gut were of the slowly‐adapting type. Some of the latter responded to intraluminal distension pressure.

6. Except for responses to succinylcholine chloride by receptors in the abdominal wall muscles and some units in the external anal sphincter, mechanosensitive receptors were not responsive to chemical stimuli.

7. The discharge rate of the receptors at the base of the feather follicles varied according to the strength of stimulus.

8. Conduction velocity of the caudal sympathetic afferent fibres ranged from 2·5 to 45 m/sec.