Relationship between the metabolic and vasodilator effects of epinephrine in human forearm muscle.

The effect of intra-arterial and intravenous epinephrine on skeletal muscle blood flow and metabolism were studied in the human forearm following complete suppression of the circulation to forearm skin by epinephrine iontophoresis. Epinephrine by either route of administration increased blood flow, O., consumption and CO;> production, and decreased arteriovenous differences of O., and CO2 across the forearm. The increments in blood flow did not correlate with the increments in O2 consumption or CO2 production. In the intact forearm intravenous epinephrine increased deep forearm venous Po2 but not venous Pco2. Hypocapnia, induced by voluntary hyperventilation, did not alter the response of forearm blood flow to intravenous epinephrine. These results show that the vasodilator response of skeletal muscle vessels to epinephrine is not dependent on decrease in Po2 or increase in Pco2 in the environment of the high resistance vessels. They also suggest that the calorigenic effect of the hormone is not a dominant factor in its vasodilator effect in skeletal muscle. ADDITIONAL