Serum and gastric tissue changes in lithium calcium and zinc ions during stress and their correlation to the gastric stress ulcers in albino rats

48 adult male albino rats of an average weight of 150 to 200 g were used to study the effect of different stressors; restraint, water immersion and cold exposure on both serum and gastric tissue Ca2+, Li+ and Zn2+ levels and their correlation with the changes in composition of gastric juice and with the development of gastric stress ulcers. Zinc sulphate pretreatment was also studied to test for a possible protective effect. The gastric juice was collected after pyloric ligation and analyzed for the volume, total acidity and proteolytic activity. Both serum and gastric tissue Ca2+, Li+ and Zn2+ were measured and the gastric mucosal lesions were scored. The ulcer and preventive indices were then calculated. The results were compared with those of a control non stressed group. It was found that all forms of stress reduced significantly the rate of gastric secretion probably secondary to gastric mucosal ischaemia. Neither the serum nor the gastric tissue levels of the gastric stimulant Ca2+, or the gastric inhibitory Li+ and Zn2+ are significantly changed and hence their role in the secretory changes and stress ulcer development was not evident. However, increasing the serum and gastric tissue Zn2+ concentration following zinc sulphate pretreatment could inhibit gastric secretion and exert a protective effect against the different forms of stress ulcer

Evaluation of some cardiovascular effects of midazolam, an imidazobenzodiazepine

Interavenous administration of midazolam in three tested dose levels [0.7, 1.4 and 2.8 mg/kg] in rabbits was accompanied directly after injection by an abrupt fall in the blood pressure. The effect was decreased with time and at the end of the 30 minutes period of exposure to the drug, the mean blood pressure returned nearly to its normal value. During the administration of each dose of the drug the heart rate remained stable till the end of the 30 minutes period of investigation and no significant changes were observed in ECG patterns of animals. On isolated perfused rabbit's heart preparation midazolam at the three tested dose levels [0.3125, 0.625 and 1.25 mg] caused a marked reduction in both the amplitude and the rate of cardiac contracion. Midazolam in a dose level of 5 mg/kg restored the normal cardiac rhythm in anaesthetized guinea pigs in which cardiac dysthrythmia was induced by ouabain and barium chloride. The drug, however, failed to reverse the cardiac dyshyrthmias induced by aconitine and digoxin. A possible correlation between the antidysrthythmic activity of midazolam and cardiac electrolyte levels is discussed