Functional subtypes of renal α1-adrenoceptor in diabetic and non-diabetic 2K1C Goldblatt renovascular hypertension

Aim: This study investigates the subtypes of the alpha(1)-adrenoceptor mediating the adrenergically-induced renal vasoconstrictor responses in streptozotocin-induced diabetic and non-diabetic 2-kidney one clip (2K1C) Goldblatt hypertensive rats. Methods: The renal blood flow responses to renal nerve stimulation, noradrenaline, phenylephrine, and methoxamine were measured in the absence and presence of nitrendipine, 5-methylurapidil, chloroethylclonidine and BMY 7378. Results: The renal vasoconstrictor responses were markedly attenuated by nitrendipine and 5-methylurapidil in the diabetic rats (all P<0.05). In the non-diabetic rats, these responses were markedly attenuated by nitrendipine, 5-methylurapidil, and BMY 7378 (all P<0.05). In both experimental groups, chloroethylclonidine markedly accentuated the renal vasoconstrictions caused by all the adrenergic stimuli (all P<0.05). Conclusion: These observations indicate that alpha(1A)-adrenoceptor subtypes play a major role in mediating adrenergically-induced renal vasoconstriction in the diabetic 2K1C Goldblatt hypertensive rats. In the non-diabetic 2K1C Goldblatt hypertensive rats, contributions of alpha(1A) and alpha(1D)-adrenoceptor subtypes were proposed. Apart from post-synaptic alpha(1)-adrenoceptors, both in the diabetic and non-diabetic 2K1C Goldblatt hypertensive rats, the potential involvement of presynaptic alpha(1)-adrenoceptors is also suggested.