. Disposition of (-) notepinephrine (NE) in the isolated caecorectal preparation of chick was studiedby recording cumulative dose response curves with (-) NE alone and in the presence of specific inhibitor of the mechanisms of amine inactivation and by using oil immersion technique. Relaxant effect of NE (10-5M) on caecorectum of chick contracted with carbachol was potentiated by about 43% with cocaine (3x 10-5M), 23% with iproniazid (10-4M) and 17% with tropolone (10-4M). The results of oil immersion technique indicated that "t50" was increased almost similarly after inhibition of uptake process, monoamine oxidase (MAO) or catechol-O methyl transferase (COMT). The results suggest that neuronal uptake was as important as the role payed by both COMT and MAO taken together.This is in contrast to that reported in mammalian tissues where the uptake process contributes mainly in the disposition of NE.

Effect of four choline esters - acetylcholine, carbachol, methacholine and betanechol were studied on perfused mesenteric vascular system of Rana tigrina. These choline esters produced vasoconstrictor responses which were. selectively blocked by very small doses of atropine.Pentolinium and dihydroergotamine partly antagonised the effects of these esters as well as that of barium chloride suggesting nonspecific effect. The results suggest the presence of muscarinic vasoconstrictor receptors in the mesenteric blood vessels of the frog similar to those described in the systemic vasculature of frog (Gambhir and Das, 1978a).

The aqueous extract of the seeds of Erythrina variegata Var. Orientalis (Sym.E. indica) produced a sharp fall in b. p. Higher dose of the extract completely stopped the heart. It also produced a contraction of isolated guineapig ileum. The fall in b.p. and contraction of ileum were completely blocked by an antihistaminic agent-diphenhydramine. The extract did not show any CNS activity, since it neither affected the barbiturate induced sleeping time nor protected the penteylene tetrazol induced convulsions although it depressed the respiration at higher doses but stimulate the same in smaller doses in guineapigs.

The effect of beta-adrenoceptor agonists and antagonists was studied on melanophore index in hypophysectomized and pinealectomized frogs. Isoprenaline and salbutamol produced dose dependent increase in melanophore index.The effect was significantly blocked by propranolol and practolol. Thus the beta agonists increase melanophore index by a direct action on melanophores. However, in the present study it has not been possible to differentiate melanophore beta adrenoceptors into beta-one or beta-two.

The beta-adrenoceptors of rabbit jejunum were investigated for their homogeneity using (-) epinephrine (E), (-)-norepinephrine (NE) and (-)-isoproterenol (IP) as the agonists. The relative order of activity for the beta-receptor sites was found to be IP>NE>E (6.23 : 1.0: 0.48). In the presence of phentolamine (2x 10-6M), bunolol yielded two different pA2 values, 6.1 with E and NE, and 7.9 with IP. However, the regression slopes of Arunlakshana-Schild plots of the three agonists in the presence of bunolol were similar.The results indicate the possibility of the existence of two types of closely related beta adrenergic receptors.

Toxicological and biochemical studies of fenitrothion, an organophosphorus insecticide, were conducted in male cats. The oral median lethal dose (LD50) of fenitrothion (98% tech. grade) was calculated to be 365 (251.7-529.2) mg/kg body weight.The oral administration of 75% of LD50 of fenitrothion produced marked toxicity signs characterstic of anti-cholinesterase poisoning during 0.5-3.0 h. and at this time there were also marked alterations in the activities of various enzymes in different tissues. After 1 h of fenitrothion administration, the cholinesterase (ChE) activity was appreciably inhibited in brain, heart and blood and remained markedly inhibited up to 24 h. The maximal increase in the levels of adenosinetriphosphate phosphohydrolase (ATPase), aspartate-aminotransferase, alanine-aminotransferase, alkaline phosphatase and acid-phosphatase in brain, liver, kidney and testes was observed at 12 h. The activities of these enzymes except ChE returned to near control values at 24 h. Plasma levels of aminotransferases and acid phosphatase also showed the similar pattern of the change.The results indicate that the observed changes in the levels of various enzymes in tissues may be due to physiological or pathological alterations induced by fenitrothion and may contribute significantly to their elevated levels in plasma.

Six closely related classes ot benzopyrones have been screened for their anti-autacoid and antiacetylcholine activity on the guinea pig ileum preparation. Their effect on histamine release upon mast cell degranulaiton by compound 48/80 has also been evaluated. Chromones were found to be the most effective benzopyrones in antagonising brady-kinin, 5-HT and acetylcholine induced contractions of the guinea pig ileum as well as in inhibiting mast cell degranulation. None of the benzopyrone produced anti-histaminic activity on the ileum preparation. 2 methyl chromone substituted at position 7 and 8 by hydroxyl, alkoxyl or acetoxyl groups showed maximum activity in all the parameters studied.

Pretreatment with ethosuximide prolonged pentobarbitone sleeping as well as induced sleep in mice treated with a subhypnotic dose of pentobarbitone. The potentiating effect of ethosuximide on pentobarhitone hypnosis has been attributed to its central dopamine receptor blocking activity.

The total alkaloids of Tylophora indica were tested for mast cell stabilising effect in comparison with disodium cromoglycate by challenging against three different mast cell degranulators, diazoxide, carbachol and polymixin B, in vitro. Both tylophora alkaloids and disodium cromoglycate prevented in similar concentrations, the mast cell degranulation occurring with diazoxide alone. Tylophora alkaloids and disodium cromoglycate did not significantly affect the carbachol and ploymyxim induced degranulation of mast cells. The results suggest that Tylophora alkaloids may have similar mechanism of action as disodium cromoglycate through cyclic AMP.

"Valmus" is bing marketed as herbal tranquillizer. Its effect had been studied on the behaviour of isolated mice. The drug as well as all its ingredients afforded significant protection.

The anti-inflammatory agents like. aspirin, phenylbutazone, indomethacin and ibuprofen were studied for drug interaction with glybenclamide in rabbits. All the agents studied excepting indomethacin interfered with glybenclamide induced hypoglycaemia. These drugs also affected carbohydrate metabolism per se as aspirin (40 mg/kg) produced hypoglycaemia and ibuprofen (10 mg/kg) hyperglycaemia. Pheaylbutazone (75 mg/kg) and aspirin (40 mg/kg) potentiated the glybenclamide induced hypoglycaemia.