Involvement of the human splanchnic circulation in pressor response induced by handgrip contraction

We have analysed the adjustment of blood flow and vascular conductance in t he abundantly supplied splanchnic circulation to a generally released press er reaction. Presser responses were induced by 2-min periods of standardize d, sustained handgrip in seven healthy students. The effects of handgrip te sts were followed both in the fasting state and after the consumption of a substantial, mixed meal. in the first of the two sessions, changes in super ior mesenteric artery blood flow were recorded and concomitant changes in l ocal vascular conductance derived, in the other session, presser released c ardiac output changes were recorded and changes in total peripheral vascula r conductance derived. Both types of flow changes were recorded using ultra sound Doppler technique. Typically, blood flow in the superior mesenteric a rtery increased two- to threefold after a meal. Handgrip contractions induc ed an initial rapid increase in heart rate, cardiac output and total periph eral conductance, followed by a gradual decline in total peripheral conduct ance and stroke volume and a gradual increase in hear? rate and mean arteri al pressure for the rest of the period. At the end of 2-min presser periods , total peripheral conductance was only about 10% below the pre-handgrip le vel, whereas vascular conductance locally in the area of the superior mesen teric artery decreased by some 30%. Thus, it appears that the splanchnic va scular bed contributes markedly to the compound presser response. Handgrips caused significantly less reduction in local vascular conductance in the p ost-prandial than in the pre-prandial state, indicating that blood flow to the digesting gastrointestinal tract retains a relatively high priority als o in a presser situation.