Distribution of alpha-adrenergic receptors in the rabbit nephron.

In order to determine the distribution of alpha-adrenergic receptors within a nephron, a method was used to determine the specific binding of [3H]-prazosin to isolated fragments of rabbit renal tubules. When 10(-8) moles/liter [3H]-prazosin was incubated with proximal convoluted tubules, 61.4% of total binding was accounted for specific binding. The [3H]-prazosin binding to the proximal convoluted tubule was a linear function of the tubular length and reversible. It was inhibited with 10(-4) moles/liter phenoxybenzamine by about 60%, and with 10(-4) moles/liter norepinephrine by about 25%, but not with either atenolol or isoproterenol. No specific binding of [3H]-prazosin was observed in the proximal straight tubule and in the cortical collecting tubule. These data are in good agreement with the view that alpha-1 adrenergic receptors are mainly distributed in the proximal convoluted tubules.