Substance-P-Induced Desensitization in Canine Cephalic Arteries is not Mimicked by Substance K, Physalaemin, or Kassinin
The responses of cephalic blood vessels to the addition of substance P or substance K were compared in canine cephalic vascular tissues. Both tachykinins relaxed precontracted segments of common carotid and basilar arteries. The addition of SP caused significant homologous desensitization but not desensitization to the subsequent addition of bradykinin, calcitonin generelated peptide or sodium nitroprusside. Comparatively little or no homologous desensitization followed the addition of SP- [4–11], SK or physa1aemin.,SP pretreatment but not pretreatment with SK kassinin physa1aemin or e1edoisin attenuated the vasodi1ating response to substance K. SK did not however, induce tachyphylaxis to the subsequent addition of substance P. Taken together these data suggest that the unique N-termina1 peptide sequence of SP mediates the tachykinin-induced desensitization within canine vascular tissues. The extent to which this mechanism accounts for tachykinin-induced desensitization in other systems remains to be determined
KeywordsSodium Nitroprusside Homologous Desensitization Carotid Artery Segment Canine Carotid Artery Cephalic Artery
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