effect of diazepam on the hypotensive action of captopril in anasthetized normotensive rats-the role of prostaglandins and angiotensin I converting enzyme

The effects of acute administration of captopril [1 mg/kg] and/or diazepam [5 mg/kg] on blood pressure and heart rate of normotensive and indomethacin pretreated rats as well as the dose-response curves of angiotensin I and II were investigated. The subacute administration of captopril and/or diazepam on blood pressure and heart rate were also studied. In the acute study diazepam prolonged the duration of the captopril-induced hypotension, while captopril abolished the diazepam-induced bradycardia. These actions have not been affected by pretreatment with indomethacin. The dose-response curve of angiotensin II was not affected by administration of captopril and/or diazepam, while that of angiotensin I was shifted to the right in response to captopril and/or diazepam in synergetic manner. Subacute administration of captopril significantly reduced blood pressure and heart rate. Similarly, subacute treatment with diazepam induced slight reduction in blood pressure and heart rate and reduced the hypertensive action of captopril. Captopril abolished the diazepam-induced bradycardia. The present study revealed that diazepam prolongs the hypotensive action of captopril, possibly by a synergetic inhibitory effect on angiotensin I converting enzyme with no saralasin-like or prostaglandin-synthesis modulating action

Imidazole protects the cardiovascular and respiratory systems against whole body gamma-irradiation "an experimental study"

The radioprotective effect of imidazole on the blood pressure, heart and respiratory rates was investigated in adult male rats. Whole body gamma-irradiation at a dose level of 6 Gy. exerted a significant hypotension and tachycardia after one and seven days post gamma-irradiation. There was a significant decrease in respiratory rate after one day of irradiation, but, a significant increase after 7 days, post-irradiation. Administration of imidazole [350 mg/kg] did not significantly affect the blood pressure, but significantly increased heart and respiratory rates after one and seven days of imidazole administration. Imidazole [350 mg/kg] 5-15 minutes before whole body, gamma-irradiation at a dose level of 6 Gy. significantly antagonised the effect of gamma-irradiation on blood pressure, heart and respiratory rates. Meanwhile imidazole completely abolished the effect of gamma-irradiation on the respiratory rate, but it did not completely abolish the effect on the blood pressure and heart rate. The results of the present investigation indicate that imidazole [350 mg/kg] is a good protector against gamma-irradiation induced changes on blood pressure, heart and respiratory rates