Effects of adenosine receptor agonists in the isolated, perfused rat kidney.

Two subclasses of adenosine receptors, A1 and A2, have been described. The purpose of these experiments was to determine and compare the renal effects of several adenosine receptor agonists: adenosine (Ado), 2-chloroadenosine (2CA, nonselective), N6-cyclohexyladenosine (CHA, A1 selective), and N6-ethylcarboxamide adenosine (NECA, A2 selective). Rat kidneys were perfused at constant pressure (105 +/- 5 mmHg) using a Krebs-Henseleit buffer containing 3.5 g/100 ml Ficoll and 1.0 g/100 ml bovine serum albumin. Three clearance periods were obtained in each kidney, i.e., control, experimental [drug at 1 microM or vehicle (NaCl)], and recovery. Perfusate flow was increased by Ado, 2CA, and NECA but not affected by CHA. Glomerular filtration was increased by NECA, decreased by CHA, and not affected by Ado and 2CA. Afferent arteriolar resistance was decreased by NECA, increased by CHA, and unaffected by Ado and 2CA. Efferent arteriolar resistance was decreased by all agonists. CHA tended to decrease renin secretio...