Role of α1 adrenoceptor subtypes in renal haemodynamics in heart failure and diabetic SD rats

摘要

Diabetes has been declared as one of the major global health hazards by the WHO and it leads to renal, cardiac and nervous tissue complications. Therefore, the present study was designed to examine the specific subclass of α adrenoceptors that are involved in the regulation of renal haemodynamics in diabetes and cardiac failure induced SD rats. Diabetes was induced by a single dose of streptozotocin (55mg/kg IP). Cardiac failure was induced by the combined treatment of caffeine and isoprenaline for seven days. On day eight the animals were anaesthetized by pentobarbitone sodium and the left kidney was exposed. The renal artery was cleared and electromagnetic flow probe was placed on it for renal blood flow (RBF) measurement. The left iliac artery was cannulated for the infusion of saline and all drugs. The renal nerves were stimulated by bipolar electrodes. The reduction in RBF to electrical nerve stimulation (1-10 Hz), bolus doses of noradrenaline (25-200 ng), phenylephrine (0.25-2.0 μ/kg) and methoxamine (1-4 μ/kg were determined before and after bolus doses of amlodipine (200 and 400 μ/kg), 5- methylurapidil (5 and 10 μ/kg), chloroethylclonidine (5 and 10 μ/kg) and BMY7378 (100 and 200 μ/kg). The results obtained indicated that the renal vasoconstrictor responses in this model were attenuated mainly by amlodipine, 5 methylurapidil and BMY7378 but not by chloroethylclonidine. The findings from this study suggest that α1A and α1D - adrenoceptors mediate the adrenergically induced renal vasoconstrictor responses in cardiac failure SD rats with diabetes.