Abstract
To elucidate the physiological characteristics of histamine receptor of the isolated renal artery in dog, effects of various receptor blockers and $Ca^{{+}{+}}$ channel blockers on the contractile responses of histamine were investigated in the isolated renal artery of dog. The results were summarized as follows: 1. Histamine caused the contraction in the isolated renal artery of dog, and the contractile responses increased between the concentration of $5{\times}10^{-6}M$ and $10^{-2}M$ in dose-dependent manner. 2. The contractile response induced by histamine ($10^{-3}M$) was not blocked by pretreatment with atropine ($10^{-6}M$), phentolamine ($10^{-6}M$), propranolol ($10^{-6}M$) or cimetidine ($10^{-6}M$), but was completely blocked by pretreatment with pyrilamine ($10^{-6}M$). 3. The contractility induced by histamine ($10^{-3}M$) was decreased in the $Ca^{{+}{+}}$ free medium. 4. The contractile response induced by histamine ($10^{-3}M$) was markedly inhibited by pretreatment with papaverine ($5{\times}10^{-5}M$) or verapamil ($5{\times}10^{-5}M$). 5. After the pre-contraction induced by norepinephrine ($10^{-7}M$) or prostaglandin $F2{\alpha}$ ($5{\times}10^{-6}M$), the contractile response induced by the additional treatment of histamine ($10^{-3}M$) was markedly increased compared with that of histamine ($10^{-3}M$) alone.