Effects of porcine galanin on the mesenteric microcirculation and arteriolar smooth muscle in the rat.

The actions of porcine galanin on the mesenteric circulation at the arteriolar level and on the isolated mesenteric small artery were studied in the rat. Male Wistar rats were anesthetized then laparotomized. Microscopic observation of the mesenteric microvascular area was made with a video camera and changes in arteriolar diameter were measured continuously with a width analyzer. Galanin (0.03-300 pmol), given intra-arterially into the mesenteric arteriole, caused an intermittent interruption of blood flow within 40 s and finally stopped the blood flow within a few minutes. The diameter of arterioles was not changed or was slightly widened. Galanin also relaxed the preconstricted small mesenteric artery in an endothelium-independent manner. Furthermore, the relaxing action of galanin was not antagonized by glibenclamide, indicating that activation of ATP-sensitive K+ channels was not involved. The present results suggest that galanin plays a modulatory role in the mesenteric circulation.