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Biomedical subjects

R K Dikshit

Publications and source records attributed to R K Dikshit.

10 recordsLinked to original sources
PubMed1995

Comparative evaluation of anticonvulsant activity of calcium channel blockers in experimental animals.

Pentylenetetrazole (PTZ)-induced convulsions and the maximal electroshock (MES) seizure test were employed to study the anticonvulsant effects of nifedipine (2, 3.5 and 5 mg kg-1), flunarizine (10, 20 and 40 mg kg-1) and diltiazem (10, 15 and 30 mg kg-1). Nifedipine and flunarizine prolonged the latent period and reduced the mean duration of PTZ induced seizures. They also reduced the severity of convulsions and the number of deaths due to PTZ significantly. Nifedipine was more potent in this regard (P < 0.01). All these drugs prolonged the latent period and reduced the duration of tonic extensor phase of MES seizures in a significant manner. Flunarizine was most potent in this test. Complete protection from tonic extensor phase was observed in 10-50% animals pretreated with nifedipine and flunarizine in a dose dependent manner. The response of diltiazem was weak in both these tests. It is concluded that all three calcium channel blockers possess an important but different anticonvulsant effect and their significant clinical use can be made while keeping in view the characteristics of their pharmacological action.

Animals↗
PubMed1994

Effect of nifedipine, a calcium channel inhibitor, on sedation produced by reserpine, clonidine and propranolol in mice.

Spontaneous motor activity, rotarod test and observational rating of sedation were employed to study effect of nifedipine on sedation produced by reserpine, clonidine and propranolol. Reserpine (2 mg kg-1), clonidine (4 mg kg-1), and propranolol (40 mg kg-1) significantly reduced spontaneous motor activity and staying capacity of animals on accelerating rotarod (P < 0.01). Observational sedation was also caused significantly as indicated by a higher score in test. Nifedipine (2 mg kg-1) produced no sedation or excitation on its own. Reduction in spontaneous motor activity produced by reserpine and clonidine was partially reversed in animals treated with nifedipine (P < 0.01). A similar effect of nifedipine was also evident on the observational sedation induced by reserpine and clonidine. Effect of these drugs on rotarod times was nearly totally antagonised by nifedipine. Nifedipine did not oppose the sedation produced by propranolol which actually became significantly greater in the animals pretreated with nifedipine in all three tests. It is concluded that nifedipine antagonizes the sedation produced by reserpine and clonidine, probably by blocking central alpha 2-adrenoceptors. The sedative effect of propranolol can be potentiated by nifedipine possibly because of a pharmacokinetic interaction.

Animals↗
PubMed1992

Rational education for rational therapy.

A sound knowledge of pharmacology and clinical therapeutics could help future prescribers in India to master the principles and practice of rational therapy. The teaching of pharmacology in medical schools should be restructured accordingly, and greater attention should be given to the applied aspects of the subject. Practicals in experimental pharmacology and dispensing pharmacy should be discontinued and useful exercises should be introduced. Methods of evaluation should be modified.

Curriculum↗
PubMed1991

Effect of calcium salts & related substances on the motility & viability of ejaculated human spermatozoa in vitro.

Effect of four calcium salts, three calcium antagonists, calcium ionophore (A 23187) and calmodulin was studied in vitro on the motility and viability of ejaculated normal human spermatozoa at different time intervals. Effect of calcium salts was also studied on the oligoasthenospermic samples with an original motility of 10 to 30 per cent. Calcium salts were found to improve the sperm motility by 6 to 16 per cent and this may be due to a direct excitatory influence and a protective action of calcium on the spermatozoa since the viability was also improved by 4 to 11 per cent in these cases. A similar improvement in motility (8 to 11%) and viability (5 to 9%) was observed in hypokinetic samples also, Calcium antagonists inhibited the sperm motility and viability significantly. Diltiazem was the most potent drug in this respect, the reduction in motility being by 11 to 22 per cent and in viability by 6 to 14 per cent, after 30 sec of incubation. Calcium ionophore and calmodulin were found to be more potent than calcium antagonists to produce a dose-dependent decrease in sperm motility and viability. The results confirm that ionized calcium plays an important role in the regulation of sperm motility. Although intracellular concentration of calcium may be a better determinant physiologically, the manipulation of extracellular levels in a critical range may promote the sperm motility, viability and other vital functions. This has a potential use in situations like artificial insemination, in vitro fertilization and semen banking. Calcium ionophores and calmodulin need further investigation for a possible use as vaginal spermicides.

Calcium↗
PubMed1987

Effect of tobacco consumption on semen quality of a population of hypofertile males.

Effect of tobacco use (by chewing or smoking) on semen quality has been seen. Semen analysis of 119 tobacco chewers and 219 smokers was compared with those of 288 control patients. Some decrease in the ejaculate volume, sperm density, and total count was observed in tobacco users, but it was statistically insignificant. No difference was found in other parameters, like motility and morphology. It is concluded that tobacco use by chewing or smoking is not associated with impaired semen quality in males selected from an idiopathically hypofertile population.

Adult↗
PubMed1987

The calcium channel antagonist, verapamil, potentiates the inhibitory action of morphine on intestinal and biliary motility.

The effects of morphine and verapamil have been assessed on the gastrointestinal propulsion of charcoal meal and egg yolk-induced gall bladder emptying in mice. Each drug significantly inhibited these functions. In combination, an additive effect was seen on the inhibition of gastrointestinal transit, whilst verapamil potentiated the morphine-induced inhibition of gall bladder emptying. It is concluded that calcium ion channel antagonists may potentiate the activity of opiate drugs.

Animals↗
PubMed1983

Possible role of dopamine in the growth inhibitory effect of pentazocine.

Growth inhibitory effect of pentazocine was studied in young rats for a duration of 4 weeks. The animals were subjected to various drug treatments, namely (1) distilled water 0.5 ml/kg s.c.; (2) pentazocine 10 mg/kg s.c.; (3) pentazocine 10 mg/kg s.c. plus metoclopramide 10 mg/kg s.c., and (4) pentazocine 10 mg/kg s.c. plus l-dopa 100 mg/kg s.c. Body weight was taken as a measure for the assessment of growth rate. The results of group 2 were compared with group 1 and that of groups 3 and 4 were compared with group 2. Pentazocine alone markedly inhibited the growth from the second to fourth weeks of treatment. Dopamine antagonist metoclopramide has almost completely prevented the growth inhibitory effect of pentazocine. Combination of l-dopa with pentazocine produced a significant growth inhibition in the first week but subsequently this effect was significantly less marked as compared to that of pentazocine alone. The growth inhibitory effect of pentazocine may possibly be mediated through alterations in dopaminergic mechanisms which are known to exert controlling influence on the release of several of the pituitary hormones.

Animals↗