REGIONAL BLOOD-FLOW REDISTRIBUTION DUE TO ACETATE

There is little information about the effects of acetate on regional blood flow in unanesthetized animals. Isosmolal sodium acetate or saline was infused at a rate of 250 mumol/kg . min into conscious rats such that, in the acetate group, plasma acetate levels averaged 2.06 +/- 0.23 mM. Sequential injections of tracer-tagged microspheres were used to determine the effect of acetate infusion on cardiac output, total peripheral vascular resistance, and various organ blood flow rates. At this infusion level, acetate had no discernible effect on either central hemodynamics or arterial blood gases. However, there was marked alteration of regional organ perfusion. After 5 min of infusion, acetate (relative to control) increased blood flow markedly to the splanchnic bed (+40 +/- 6.1%), including all individual splanchnic organs except for the stomach. Acetate also increased blood flow to the heart (+33 +/- 5.2%) and kidneys (+29 +/- 5.4%); all P < 0.05. Acetate had no specific effect on total cerebral blood flow or on regional brain circulations. Acetate had no effect on flow to skeletal muscle (-30 +/- 11%; P = not significant) or fat (-5 +/- 6.3%; P = 0.097), although flow to muscle tended to decrease. These data suggest that low plasma levels of acetate, which do not alter total peripheral resistance, cause a marked redistribution of blood flow to the splanchnic organs and to the kidneys. Brain blood flow is unaffected.