Investigation into the possible mechanisms involved in altered digoxin levels in diabetic patients.

The present study was undertaken to investigate the possible factors which may contribute to the altered digoxin levels in diabetic patients. The digoxin levels were found to be significantly higher in diabetics (1.74 +/- 0.09 ng/ml) as compared to non-diabetics (0.76 +/- 0.07 ng /ml). There was a positive correlation between digoxin levels and glycosylated haemoglobin levels. All diabetic patients had serum creatinine, urea and potassium levels within normal limits. However, serum TSH levels were found to be significantly higher in diabetics as compared to controls. Serum tri-iodo-1-thyronine (T3) levels were found to be lower in diabetics as compared to non-diabetics. Our data suggests that diabetes-mellitus causes alteration of digoxin levels. One of the causes of this increase in digoxin levels may be a tendency towards mild hypothyroidism associated with diabetes mellitus.

Involvement of K+ channels in the relaxant responses to various agonists in estrogen primed rat uterus.

The present investigation was undertaken to study the effects of K+ channel openers in the relaxant responses to various agonists in estrogen primed rat uterus. Adrenaline and isoprenaline produced a dose-dependent relaxation in the estrogen primed rat uterus. The relaxant responses were found to be significantly potentiated when the preparations were exposed to PSS devoid of calcium. The responses to isoprenaline were found to be greater in the preparations depolarized with 40 mM KCl instead of 80 mM KCl. KCl failed to produce any contractile effect in the presence of D-600. Further, the addition of D-600 completely relaxed the KCl depolarized rat uterus. Pinacidil and cromakalim failed to relax 80 mM KCl depolarized rat uterus. However, they produced dose-dependent relaxation in the preparations depolarized with 40 mM KCl. The relaxant responses to pinacidil and cromakalim were competitively blocked by procaine. However, they were not altered by either propranolol or cimetidine. The relaxant responses to isoprenaline and histamine were found to be potentiated by pinacidil and cromakalim. These results indicate that in rat uterus in addition to adenylate cyclase c-AMP, potassium channels are also involved in the relaxant responses to isoprenaline and histamine.

Effect of mepyramine on the histaminase release induced by heparin injection and anaphylaxis in guinea pigs.

Injection of heparin as well as antigenic challenge in sensitized guinea pigs are known to produce a release of histaminase into the plasma. In the present study, tissue histaminase estimation was done by Spencer's method (17) and plasma estimation by Kapellar Adler's (7) method. Mepyramine pretreatment considerably decreased the histaminase release by both heparin and anaphylaxis. Mepyramine did not antagonise the anticoagulant action of heparin in vitro.

Some photoresponses of isolated tissue preparations to ultraviolet light in the presence of photosensitizers.

Responses of isolated tissue preparations to ultraviolet (UV) light were studied with and without the presence of photosensitizers like eosin, fluorescein and sodium nitrite. Exposure to UV light in the presence of sodium nitrite induced consistent relaxation of rat duodenum. The photorelaxation was found to be related to the concentration of sodium nitrite. Adrenergic or cholinergic mechanisms do not seem to be involved. The isolated rat duodenum preparation exhibited quantitatively consistent photoresponse for 3 to 4 hr at its normal tone obviating the need for additional spasmogens as needed with other preparations. The preparation is a suitable test model for the study of photobiologic response evoked by UV light.

A simple method for continuous recording of perfusion rate of blood vessels of frog.

A method for continuous registration of perfusion rate of frog blood vessels has been developed utilizing a modified Marey's tambour with lever system, connected to the perfusion bottle. The responses of frong blood vessels to some autonomic drugs have been studied using this method.

Isolated innervated, rat and guinea-pig hemi-urinary bladder preparations.

Isolated innervated hemi-urinary bladder preparations of the rat and the guinea-pig have been described. In durability and behaviour to different frequencies of stimulation, the guinea-pig hemi-bladder is shown to give comparable results to those reported for the whole nerve-bladder. The rat hemi-bladder gave less durable contractions on prolonged stimulation. It is shown that the isolated guinea-pig hemi-bladder can be substituted for the isolated whole bladder preparation.