. Pretreatment with L-histidine, precursor of histamine, was found to potentiate haloperido1 induced catalepsy and to antagonise methamphetamine stereotypy while pretreatment with chlorcyclizine, a H1-receptor blocker, was found to antagonise haloperidol catalepsy and to potentiate methamphetamine stereotypy: Further, chlorcyclizine was found to antagonise the potentiating effect of L-histidine on haloparidol catalepsy and also the inhibitory effect of L histidine on methamphetamine stereotypy. Our results indicate that the central histaminergic system by exerting a modulatory influence on the striatal dopaminergic system may influence the functioning of the extrapyramidal motor system.

. The effect of bacterial endotoxin (TAB vaccine and Shigella dysenteriae somatic type 0 antigen) and the prostaglandins (PCs) has been studied on the cloacaI temperature of unanaesthetized pigeons. The endotoxin produced hypothermia which showed little dose dependance and which w as more marked after intravenous than after intracerebroventricular injection and a very delayed hyperthermia brought in relief by the circadian rhythm of the body temperature. The PGs E1 E2 F1and F2 were devoid of temperature effect when injected intraventricularly at ambient temperature between 10(-30(C. Injected intravenously, PGE, produced a small hypothermia. Intravenous injection of indomethacin, an inhibitor of PG synthesis, neither affected the normal temperature nor modified the endotoxin hypothermia. It is inferred that PGs are not involved in themoregulation and the early hypothetic effect of the endotoxin may be due to its direct action on the skin blood vessels.

. Histamine depletes the noradrenaline levels in different regions of rat brain when administered intracisternally. A decrease in the catecholamine level could also be effected by 2-(2-pyridyl) ethylamine (H1-agonist) and compound 48 / 80 (histamine releaser) or following histidine loads to the animals.This decrease in noradrenaline levels could not be observed if the animals are pretreated with H1-antagonists. The results, in conjunction with the in vitro data documented, suggest the cerebral effects of histamine are at least in part mediated by modulation of the noradrenergic processes.

. Various pharmacological activities of a new 2-substituted pyrazinopyridoindole antihistaminic compound ethamidindole were investigated in cat, rabbit, guineapig and mouse by various in vivo and in vitro techniques. The compound produced a weak sedative, hypotensive and local anaesthetic effect. It was devoid of anticonvulsant, analgesic, anti-inflammatory, anti-arrhythmic and neuromuscular blocking activity.

Dehydroemetine (DHE) caused a reversible blockade of contractile responses due to field stimulation of vas deferens preparation of rat. Unlike other adrenergic neurone blockers such as guanethidine, dextroamphetamine did not prevent the neurone blocking action of DHE and the responses of exogenously added norepinephrine (NE) were antagonised by DHE. The responses due to 5-hydroxytryptamine (5-HT) and KC1 were antagonised noncompetitively by several concentrations of DHE (1.8 x 10-5 M, 3.6 x 10-5M and 7.2 x 10-5M). The computation of pD2 values of different concentration of DHE suggested a common site of action. 3.6 x 10-5 M of DHE, which showed noncompetitive antagonism against all the three agonists NE, 5-HT and KC1 antagonised the Cacl2 , induced contractible responses in depolarised preparations competitively. It is concluded that DHE exerts a nonspecific antagonistic action by interfering with exitation-contration coupling mechanism and its neurone blocking effect does not resemble that of a classical neurone blocker such as guanethidine.

. Histamine (l-4(g/ml), 4-methyl histamine (l00-400(g/ml), an H2-receptor agonist and 2-( 2-aminoethyl) pyridine (20-80 'g/ml), an H1-receptor agonist produced dose dependent contractions of the guineapig isolated seminal vesicle. Histamine responses were blocked partially by matiamide (1 'g/ml), an H2-antagonist and to a great extent by mepyramine (0.1 'g/ml) an H1-antagonist. Log dose response curves of histamine showed parallel shift to right in the presence of these antagonists. There was a delay in the initiation of histamine induced contraction in presence of metiamide. Mepyramine could block all the agonist responses effectively, whereas metiamide could block only the histamine and H2-agonist responses partially, the effect on H1-agonist responses being negligible. The results reveal the presence of both H1- and H2-receptors in guineapig seminal vesicle, both subserving a contractile response which is mostly mediated through H1-receptors, the H2-receptors playing only a minor role probably during the initiation of response.

. Histamine and 4-methylhistamine (4-MH), a specific H2-receptor agonist produced dose related relaxation of uterine strips obtained from estrogen primed rats, while 2-(2-pyridyl) ethylamine (PEA), a specific H,-receptor agonist had no significant effect. Metiamide, the specific H2-receptor antagonist inhibited the responses to histamine and 4-MH, while mepyramine maleate, the specific H1- receptor antagonist did not produce any significant effect. Propranolol, the classical adrenergic beta-receptor antagonist also inhibited histamine and 4.MH induced relaxation of the estrogen primed rat uterus. Reserpine pretreatment (5 mg/kg) significantly reduced the histamine and 4-MH responses. Our findings suggest that histamine acts indirectly on the uterus to produce inhibition by stimulating H. receptors. H1-receptors do not appear to be present in the rat uterus.

. Present work was undertaken to study the effects of sodium bicarbonate and ammonium chloride on absorption and elimination kinetics of three sulfonamides. Alteration in urinary pH ranging from 5 to 8 did not show statistically significant Difference in total urinary excretion of sulfonamides during six hours of the study with different treatments. Apparent higher clearance of sulfonamides was observed during initial period of the study. It was concluded from the results that slow rate of absorption of sulfonamides with ammonium chloride treatment might be contributing to some extent to slow clearance of sulfonamides in acidic urine during initial period of the study.

. Ethamidindok a new Z-substituted pyrazinopyridoindole, showed antihistaminic activity in cat, rabbit and guineapig in various in vivo and in vitro test models. The antagonism was competitive like that of mepyramine. It also inhibited the antigen induced contraction of the intestine of sensitized guineapigs. Both the peripheral and central effects of histamine, mediated via H1-receptors were antagonised by ethamidindole. The compound was well absorbed from the intestinal tract of cats. Ethamidindok was, however, less potent than mepyramine.

. The anti-allergic effect of Tylophora indica was compared with that of disodium cromoglycate on perfused rat lung in sensitized rats by observing the changes in the volume of the perfusate per minute. The rats were semitized with Freund's adjuvant and bovine albumin 0.05 ml each given intraperitoneally. Aqueous extract of Tylophora indica (5% soln.) was administered intraperitoneally (5 mg/kg) 3 days prior to sensitization. The rate of flow increased from 7.65 to 19.55 ml/min (P<0.05). Administration of aqueous extract of Tylophora indica and disodium cromoglycate during perfusion of sensitized rat lung significantly increased the rate of flow.The action of Tylophora indica may be due to direct bronchodilator property and membrane stabilising and immuno-suppressive effects.

. The test for freedom from pyrogens in aminophylline injection is not prescribed in any pharmacopoeia probably in the belief that theophylline contained in aminophylline injection, being a xanthine derivative, may interfere with the pyrogen test because of its antipyretic property. This investigation reveals that doses of aminophylline as high as 25 mg/kg do not interfere with the official test in rabbits and that when the sample was contaminated with a pyrogenic material, a rise in temperature was observed.The inclusion of the test for freedom from pyrogens in aminophylline injection in the official compendia is therefore recommended.

. Both the alcoholic and aqueous extract obtained from fresh stem of Euphorbia nerifolia Lii. revealed significant local anaesthetic activity following the test on intradermal wheal in guinea-pig and foot-withdrawal reflex in frog.