Human and rat resistance vessels: a comparison of their morphological and pharmacological characteristics.

The morphology and pharmacology of isolated human omental and rat mesenterial resistance vessels of about 200 micron i.d. have been compared. The results show a similarity in the gross morphology, the maximal responses and the sensitivity of the smooth muscle cells to noradrenaline and Ca2+. There were differences in the vascular smooth cell size and minor qualitative differences in the pharmacological responses. More importantly, we found that there was a very sparse adrenergic innervation of the human vessels as compared to the rat vessels, suggesting that these human vessels may not be under sympathetic control. The results suggest that, with the exception of the differences noted, the rat vessels are a reasonable model for the human vessels.