Regulation of splanchnic perfusion

In splanchnic arteries, vasodilators decrease the cytosolic free calcium concentration ([Ca2+]i) by inducing Ca2+sequestration and extrusion, by limiting the entry of extracellular Ca2+via L-type Ca2+channels and by decreasing the agonist-induced mobilization of intracellular Ca2+. Cyclic GMP kinase and membrane hyperpolarization are important mediators of the decrease in [Ca2+]i. Vasoconstrictors increase [Ca2+]i by mobilizing intracellular Ca2+from the sarcoplasmic reticulum and by stimulating extracellular Ca2+entry via L-type Ca2+channels. Activation of G proteins, inositol trisphosphate, diacylglycerol and membrane depolarization are important mediators of the increase in [Ca2+]i.