Hemodynamic Responses Elicited By γ2-MSH or Blood Replacement in Hemorrhaged Rats

These findings suggest that although γ2-MSH elicits pressor and vasoconstrictor responses in hemorrhaged rats, the bolus injection of this peptide may not in itself be an effective strategy for the sustained restoration of MAP in these rats. Moreover, although blood replacement effectively restores MAP via increases in cardiac output rather than total peripheral resistance, it appears that this manipulation produces an active vasodilation in the hindquarter bed. The possibility that this vasodilation involves a sympathetic neurogenic vasodilator system, which innervates the hindlimb vascular bed but not mesenteric or renal vascular beds, will be discussed.