Evaluation of hypoglycemic and antihyperglycemic effects of Datura metel (Linn.) seeds in normal and alloxan-induced diabetic rats.

The seed powder of Datura metel was tested for its hypoglycemic activity in normal and alloxan-induced diabetic rats. Graded doses (25, 50 and 75 mg/kg, p.o.) of the seed powder when given to both normal and diabetic rats produced significant reduction in blood glucose at the 8 h. The effect was found to be dose dependent with all treatments at the doses administered.

Infarct size limiting effect of apstatin alone and in combination with enalapril, lisinopril and ramipril in rats with experimental myocardial infarction.

Bradykinin is a potent vasoactive peptide that is known to elicit a number of biological responses. A number of peptidases have been identified to possess kininase activity, the inhibition of which increases the availability and effectiveness of kinins. We wished to determine the cardioprotective actions of an aminopeptidase P inhibitor, apstatin alone and in combination with enalapril/lisinopril/ramipril in an in vivo rat model of acute ischemia (30 min) and reperfusion (4 h). Myocardial infarction was produced by occlusion of the left anterior descending coronary artery for 30 min followed by 4 h of reperfusion. Infarct size was measured by using the staining agent 2,3,5-triphenyl tetrazolium chloride (TTC). Lipid peroxide levels in serum and in heart tissue were estimated spectrophotometrically. A lead II electrocardiogram was monitored at various intervals throughout the experiment. Infarct size was reduced to a greater extent with apstatin and with combined inhibition it was further reduced. Infarct size reduction obtained with the combined inhibition came to normal with the prior administration of B2 bradykinin antagonist HOE140 suggests the involvement of bradykinin in the cardioprotective actions of apstatin.

Biochemical, histological and echocardiographic changes during experimental cardiomyopathy in STZ-induced diabetic rats.

Diabetes mellitus is associated with an increased susceptibility to cardiovascular disease and it has been suggested that alterations in myocardial function may contribute to the development of diabetic cardiovascular complications. The objective of the present study is to examine the left ventricular (LV) function in streptozotocin (STZ)-induced diabetic rats in a definite course of time by non-invasive methods, i.e. M-mode and Doppler echocardiography. From the results, it was found that treatment of animals with STZ resulted in increase in blood glucose, triglycerides, cholesterol, low density lipoproteins (LDL) and decrease in serum total protein levels. Echocardiographic studies revealed that LV internal dimension (mm) during systole was significantly increased after 12 weeks of diabetes when compared to base line data of the same animals and with control animals 6.50+/-0.13 versus 4.25+/-0.17, versus 4.34+/-0.25 (P<0.05), however there was no significant change after 4-8 weeks of diabetes. Also LV internal dimension (mm) during end diastole increased significantly only after 12 weeks of diabetes than to base line data of the same animals and with control animals 7.71+/-0.34 versus 6.18+/-0.25, versus 6.25+/-0.18 (P<0.05). Fractional shortening (%), 15.69+/-5.1 versus 31.22+/-1.7, versus 30.56+/-2.1 (P<0.05), and ejection fraction (%) 37+/-2.31 versus 68.18+/-2.8, versus 60.32+/-3.5 (P<0.05), differ significantly after 12 weeks of diabetes when compared to base line data of the same animals and with control animals. E-wave (cm/s) was significantly decreased after 12 weeks of diabetes 21.11+/-1.5 versus 35.19+/-4.5, versus 32.75+/-3.0 (P<0.05), and A-wave (cm/s) was significantly increased after 12 weeks of diabetes 34.88+/-4.2 versus 19.21+/-2.8, versus 20.59+/-2.1 (P<0.05); thus, diabetic animals after 12 weeks had an inversed E/A ratio. Histological studies revealed that after 8 weeks of diabetes, necrosis was minimal, but after 12 weeks of diabetes extensive focal endomyocardial necrosis was observed. From this study, we conclude that overt LV systolic and diastolic dysfunction was fully visible at 12 weeks of diabetes on echocardiography and this non-invasive technique of echocardiography is useful in diagnosing LV dysfunction in diabetic rats without the need of invasive histopathological procedures.

Studies on the involvement of bradykinin using enalapril and 2-mercaptoethanol in ischemia-reperfusion induced myocardial infarction in albino rats.

The effects of bradykinin were evaluated using the ACE inhibitor enalapril and the APP inhibitor, 2-mercaptoethanol alone and in combination in rats with experimental myocardial infarction. Myocardial infarction was produced by occlusion of the left anterior descending coronary artery for 30 min followed by 4 h of reperfusion. Infarct size was measured by the TTC stain method. Lipid peroxide levels in serum and heart tissue were estimated by the methods developed by Yagi and Ohkawa et al., respectively. A lead II electrocardiogram was monitored throughout the experiment. With the combined inhibition of both the enzymes ACE and APP, a better cardioprotection was observed when compared to individual inhibition of the enzymes, suggesting the involvement of bradykinin during experimental myocardial infarction.

Studies on the signal cascade mechanism mediating the cardioprotective actions of bradykinin.

The cardioprotective involvement of bradykinin was evaluated using the ACE inhibitor, lisinopril, and the APP inhibitor, 2-mercaptoethanol alone and in combination in rats with experimental myocardial infarction. The signal cascade mechanism mediating the cardioprotective actions of bradykinin was evaluated by administering aspirin and methylene blue prior to lisinopril and 2-mercaptoethanol combined treatment. Myocardial infarction was produced by occlusion of the left anterior descending coronary artery for 30 min followed by 4 h of reperfusion. Infarct size was measured by the TTC stain method. Serum free radical levels were estimated by the method developed by Yagi. A lead II electrocardiogram was monitored throughout the experiment. With the combined inhibition of both the enzymes ACE and APP, a better cardioprotection was observed. The observed cardioprotection was decreased with the prior administration of aspirin and methylene blue. The results suggest the cardioprotective role of bradykinin during experimental myocardial infarction. The results are further suggesting the involvement of both prostaglandins and nitric oxide pathways in the cardioprotective actions of bradykinin.