The role of histamine receptors in the release of renin.

1 The effect of intrarenal histamine, dimaprit (H2-agonist) and 2-(2-pyridyl) ethylamine (H1-agonist) on renin release was examined in anaesthetized dogs. 2 In dogs with intact kidneys, histamine and dimaprit administration resulted in renal vasodilatation, a two fold increase in urinary sodium excretion, and no change in renal renin release. 2(2-Pyridyl) ethylamine administration resulted in renal vasodilatation, a 25% decrease in urinary sodium excretion and a significant increase in renin release. 3 In dogs with non-filtering kidneys, dimaprit administration resulted in renal vasodilatation and a significant increase in renin release, while 2(2-pyridyl) ethylamine administration resulted in renal vasodilatation but no change in renin release. 4 Our data suggest that histamine is a potential participant in the release of renin through stimulation of H2-receptors, but it is a weak agonist. 5 In addition, the direct effect of histamine analogues on renin release is modulated by their effects on electrolyte excretion probably by influencing the renal chemoreceptor release of renin mediated by the macula densa.