The characteristics of alpha-adrenoceptors mediating the renal nerve induced antinatriuresis and antidiuresis in hypertensive rats

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Selective α-adrenoceptor and calcium antagonists have been used to determine both the α1-adrenoceptor subtype and the extracellular calcium requirement for renal nerve-mediated antinatriuresis and antidiuresis in deoxycorticosterone acetate (DOCA)-salt and two-kidney, one clip (2K1C) Goldblatt hypertensive rats. Stimulation of the renal nerves at low frequencies reduced urine flow and absolute and fractional sodium excretions by 40-60% in pentobarbitone anaesthetized control, sham-operated, DOCA-salt and 2K1C Goldblatt hypertensive rats. Administration of prazosin, but not idazoxan, inhibited the renal nerve-induced excretory responses in both models of hypertension, a result compatible with the involvement of α1-adrenoceptor. By contrast, the calcium antagonist inhibited the renal nerve-dependent antinatriuresis and antidiuresis in DOCA-salt but not 2K1C Coldblatt hypertensive rats. These results showed that the renal nerves mediated their action via α1-adrenoceptor, but that the postreceptor responses were dependent on extracellular calcium in DOCA-salt but not 2K1C Goldblatt rats.

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