Splanchnic blood flow reduction

It induces direct contraction of vascular smooth muscle, leading to a reduction of portal and splanchnic blood flow. 

Reduction of portal pressure. Vasopressin (anti-duiretic hormone, see p. 711), in addition to its action on the renal collecting ducts (through receptors), constricts smooth muscle (Vj receptors) in the cardiovascular system (hence its name), and particularly in splanchnic blood vessels, so reducing blood flow in the portal venous system. Unfortunately, coronary vasoconstriction can also occur, and treatment has to be withdrawn from 20% of patients because of myocardial ischaemia. Glyceryl trinitrate (transdermally, sublingually, or intravenously) reduces the cardiac risk and, advantageously, further reduces portal venous resistance and pressure. 

Although ganglionic blockade decreases total systemic vascular resistance, changes in blood flow and vascular resistance of individual vascular beds vary reduction of cerebral blood flow is small unless mean systemic blood pressure falls below 50-60 mm Hg skeletal muscle blood flow is unaltered splanchnic and renal blood flow decrease. 

Trlvastal, E-k95, (V) is primarily a vasodilator causing selective increase in femoral blood flow while decreasing splanchnic flow. It caused a reduction in blood pressure, heart rate and respiration which was liihlbited by vagotomy. ... 

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