Search Results
You are looking at 1 - 9 of 9 items for
- Author: R. R. CHAUDHURY x
- Refine by access: All content x
Search for other papers by H. DATTA in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
A pharmacological agent which could block the antidiuretic effect of antidiuretic hormone (ADH) would obviously have many uses. It could (a) be a diuretic with a new mechanism of action, (b) help in the diagnosis and possibly the treatment of the Schwartz-Bartter Syndrome (Thorn & Transbol, 1963) and ADH-secreting tumours (Ross, 1965) in the acute phase of inappropriate ADH secretion and hyponatremia, (c) elucidate the role of ADH in oedema, (d) be useful in the bioassay of ADH in body fluids to determine the specificity of the antidiuretic substance being measured. At present the only test for specificity commonly performed is incubation of the antidiuretic substance with sodium thioglycollate (Ames & van Dyke, 1951). If an ADH antagonist were available it could be administered to the assay rat and would block the effect produced by ADH alone thus indicating whether the antidiuretic substance assayed was ADH.
In an effort to
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Search for other papers by M. MATTHEWS in
Google Scholar
PubMed
It has been generally accepted that oxytocin is released during coitus by the female rat, rabbit and the lactating woman (Harris, 1955). The physiological significance of this release of oxytocin is not clear, but Harris (1947) has suggested that in the rabbit, coitus stimulates the neurohypophysis by a nervous reflex to liberate oxytocin which increases the motility of the uterus and thus helps in the transport of seminal fluid up the female reproductive tract. If the oxytocin released during coitus is responsible for sperm transport, an agent which prevents the release of oxytocin might prevent sperm ascent and fertilization. Chaudhury (1960) has shown that a 7·5–10 % ethanol solution administered to female rats in a volume of 5 ml./100g. body wt. inhibits the release of oxytocin in response to the suckling stimulus as assessed by a block in milk ejection. Fuchs & Wagner (1963) have confirmed these findings and have shown
Search for other papers by J. RUSSELL in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Although the release of oxytocin from the neurohypophysis has been demonstrated both after physiological stimuli such as suckling (Fitzpatrick, 1961) and after administration of pharmacological agents such as nicotine (Bisset & Walker, 1953), very little work appears to have been carried out to investigate how quickly oxytocin is repleted at the posterior pituitary gland after release. In the present investigation the oxytocin content of the pituitary gland was determined at 2, 10, 30 and 120 min after intravenous administration of nicotine to rats. The effect of previous administration of pheniramine, an antihistamine, on the oxytocin-releasing action of nicotine was studied in a further series of experiments.
Male albino rats (150–200 g) were used. Nicotine bitartarate at a dose of 1 mg/kg was injected slowly into the tail vein of the rat. Groups of rats were killed by decapitation at 2, 10, 30 and 120 min after the administration of nicotine.
Search for other papers by H. DATTA in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Datta & Chaudhury (1968) have shown that [Asp4]-oxytocin, [Ile8]-oxytocin and [Ser4]-oxytocin block the antidiuretic effect of antidiuretic hormone (ADH) when administered 10 min. before it. Further investigations on the mechanism of this blocking effect of [Asp4]-oxytocin are reported in this communication. The first series of experiments were carried out to see if [Asp4]-oxytocin could also block the vasopressor effect of ADH. Adult male rats (250–300 g.) were anaesthetized with urethane (1.4 g./kg.) and the blood pressure recorded on a smoked drum through a cannula in the carotid artery. The external jugular vein was cannulated for administration of the drugs. ADH (arginine vasopressin) was administered at a dose ranging from 0·25 to 4·0 m−u. before and 10 min. after administration of [Asp4]-oxytocin in eight animals. The same dose of ADH was administered before and after [Asp4]-oxytocin which
Search for other papers by K. S. RAGHAVAN in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Although various hypotheses have been suggested to explain the mechanism of the antifertility effect of an intrauterine device (IUD), this mechanism is not known. It has been suggested that studies on the effect of an IUD on the blood level of oxytocin be carried out (W.H.O. Tech. Report No. 397).
In this investigation the circulating level of oxytocin in the plasma of rats with and without bilateral IUD's has been estimated both at oestrus and dioestrus. The IUD, a silk thread suture, was inserted as described by Chaudhury & Tarak (1965). The method of extraction of oxytocin from rat plasma was that of Folley & Knaggs (1965).
Female albino rats weighing 175–225 g. were used. Blood was collected from decapitated animals into chilled polythene beakers containing 500 i.u. heparin. Blood from three to eight animals was pooled. Plasma was obtained by centrifugation at 4° at 3000 rev./min. for 20 min.
Search for other papers by S. C. SHARMA in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
This investigation was carried out to study the uterus-stimulating activity of the plasma of male rabbits before and after mating to see whether there was any change. Twenty experiments were performed where blood from the male rabbit was collected by means of intracardiac puncture before and 2½ min. after mating. Ice-cold polythene syringes and tubes were used for the collection of blood, and the plasma was assayed on the isolated rat uterus (Holton, 1948). The oxytocic activity was assayed against synthetic oxytocin or against a freshly prepared solution of 5-hydroxytryptamine (5-HT) in two groups of ten rabbits each. In five out of ten experiments in each group, the rat uterus in a 10 ml. bath was treated with 50 μg. dichloroisoproterenol (DCI) for 20 min. to ensure that adrenaline in the plasma would not interfere with the assay (Levy & Tozzi, 1963).
In those experiments where the plasma was assayed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Search for other papers by J. M. WALKER in
Google Scholar
PubMed
SUMMARY
Oxytocin injected intravenously into anaesthetized rabbits disappears rapidly from the blood stream, and its disappearance is retarded in animals whose liver or kidneys have been excluded from the circulation. The rate of disappearance of injected vasopressin is similar to that of oxytocin in intact rabbits. Homogenates of rabbit liver and kidney inactivate oxytocin rapidly in vitro; the site of inactivation by the kidney is in the tubules and not in the glomeruli.
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
Search for other papers by G. F. JOPLIN in
Google Scholar
PubMed
SUMMARY
1. Oxytocic and vasopressor activity were found in human peripheral venous blood following overnight dehydration and an intravenous injection of nicotine.
2. The quantities are adequate for investigation of hypothalamic damage of moderate severity.
3. The blood levels of oxytocic activity exceed vasopressor activity.
Search for other papers by M. N. BURJORJEE in
Google Scholar
PubMed
Search for other papers by U. MALHOTRA in
Google Scholar
PubMed
Search for other papers by R. R. CHAUDHURY in
Google Scholar
PubMed
SUMMARY
The oxytocin-inactivating activity (OIA) of rat uterus homogenates was studied in intact animals and in animals with bilateral intrauterine devices (IUD). In another series of experiments the OIA of the rat uterus was related to the mast cell count of uteri from intact rats and from rats with bilateral intrauterine devices. The OIA of the homogenates was significantly higher at oestrus than at dioestrus. No such increase was observed in homogenates from rats at oestrus with bilateral IUD's. The IUD caused an increase in the mast cell population at oestrus and the increase in mast cell counts observed in uterine homogenates of intact rats at dioestrus was not observed in the presence of a device. No correlation between the OIA of uterine homogenates and the mast cell population was observed in animals with or without IUD at oestrus or dioestrus.