Baroreflex control of the XXXX tail circulation in normothermia and @entity221 .

@entity8331 @entity548 @entity2647 @entity432 @entity35 @entity221
The role of thermoregulatory background in the baroreceptor reflex control of the tail circulation was investigated 1) in anesthetized @entity35 with a constant flow technique and 2) in conscious @entity35 by measuring tail blood flow ( @entity432 plethysmography). In series I, during normothermia, systemic intravenous @entity2647 infusion increased mean arterial pressure (MAP) by 61.0 +/- 3.6 mmHg and induced a reflex decrease in tail perfusion pressure ( @entity8331 ) from 105.0 +/- 6.3 to 84.2 +/- 4.4 mmHg (P less than 0.005). @entity221 decreased @entity8331 to 66.5 +/- 5.1 mmHg (P less than 0.001) and abolished the @entity8331 response to increased MAP (P greater than 0.05). Increases in MAP via systemic infusion of whole blood caused reductions in @entity8331 during normothermia but failed to reduce @entity8331 further during @entity221 . Graded decreases in MAP during both normothermia and @entity221 caused tail vasoconstriction. The increase in @entity8331 was greater (P less than 0.025) during @entity221 . In series II, conscious animals showed similar responses to @entity548 . Graded decreases in MAP produced graded decreases in tail vascular conductance (TVC, ml.100 ml-1.min-1.100 mmHg-1). The slope of the TVC-MAP relationship averaged 0.011 +/- 0.003 TVC U/mmHg during normothermia and was markedly steeper (P less than 0.01) during @entity221 (1.99 +/- 0.39 TVC U/mmHg). Thus the participation of the cutaneous vasculature of the @entity35 in baroreceptor reflexes depends on thermal status, probably through the level of background sympathetic vasoconstrictor nerve activity.
