The regulation of the cutaneous circulation is of paramount importance and is extremely complex. It is mediated by the sympathetic nervous system both locally, through the release of catecholamines from the sympathetic nerve terminals, and systemically, through their release into the general circulation by the adrenal medulla. In recent years, and with newer molecular genetic techniques, the simple model of 2 adrenergic receptors (adrenoceptors) that mediate the vascular response to catecholamines8 has been replaced. The concept of “generic” α-adrenergic receptors, responsible mostly for “excitatory” functions such as vasoconstriction and uterine and urethral contraction, and “generic” β-adrenergic receptors, responsible mostly for “inhibitory” functions such as vasodilatation, bronchodilation, and uterine and urethral relaxation (though notably inotropic for the heart) has been further refined and specific receptor subtypes, localizations, and functions have been elucidated. The current model is that of a complex family of structurally related receptors consisting of at least 6 α-receptor subtypes (α1A [α1a/c], α1B, α1D, α2A [α2A/D], α2B, and α2C) and at least 3 β-receptor subtypes (β1, β2, and β3),9- 13 with additional conformational variants such as α1L and β4 bringing the total number of functional adrenoceptor conformations to at least 11.