Responses of rabbit renal artery to histamine: receptor type and temperature dependence

The effects of histamine on spiral strips of rabbit renal artery have been recorded. Histamine causes dose-dependent contractions of this preparation which are not antagonized by the H2 receptor blocking agent metiamide, but which are blocked by the H1 antagonist diphenhydramine. The pA(2) for the latter agent is similar to that observed at 37 degrees C in intestinal smooth muscle. No evidence of a relaxant population of H2 receptors was encountered. Unlike that of intestinal smooth muscle, the response of strips of renal artery becomes progressively diminished at temperatures below about 20 degrees C, and the effect of reduced temperature on receptor subtype is thus more difficult to assess. It appears, however, that there is no change in type from the H1 receptor observed at 37 degrees C and thus the temperature-dependent transformation which has been reported previously does not occur in all H1 systems.