Muscle and skin blood flow and metabolism during states of decreased activation.

Acute decline of forearm oxygen consumption has been observed during an acute, wakeful behaviorally induced rest/relaxed state. This change of tissue respiration was not associated with variation of rate of forelimb lactate generation. Since forearm blood flow did not change significantly during this behavior, the decline of oxygen consumption by forearm was due almost solely to decreased rate of oxygen extraction. Decreased muscle metabolism was a likely contributor to these observations. The occurrence of sleep was not related to the metabolic change. The lack of coupling between the metabolic and blood flow changes during this state of decreased activation suggests limitation of the hypothesis of obligatory coupling between systemic and/or regional cardiovascular and metabolic function.