Impaired Chronotropic Response to Exercisein Mice Lacking Catecholaminesin Adrenergic Cells

摘要

To define the in vivo role of adrenergic catecholamines (CAs), we generated a mouse model whereby tyrosine hydroxylase (TH) was knocked out (KO) in phenylethanolamine N-methyltransferase—expressing cells. These adrenergic specific TH-KO mice were vi-able and grossly normal. Their resting heart rate and blood pressure, as monitored by telemetry, were unchanged. However, when challenged with treadmill exercise, their chronotropic responses were significantly reduced by 14% compared to wild-type mice. Thus, our data suggest that adrenergic CA is required for normal chronotropic re-sponses to stress, but not required for prenatal and postnatal development or normal cardiovascular function at rest.