Cardiovascular Actions of Lead in Rats as Related to the Level of Chronic Exposure
A marked increase of both blood pressure (BP) and cardiac inotropism (CI), without chronotropic changes, was found by Iannaccone et al. (1981) and Carmignani et al. (1983) in anesthetized male rats fed 50 ppm lead (Pb) for 160 days (average blood Pb of 38.4 μg/dl). These rats showed baroreflex hyposensitivity, sympathetic hyperactivity, a possible decreased conversion of angiotensin I (Al) to angiotensin II (A2), and an increased cardiac and vascular responsiveness to some α1–2- and β1–2-adrenoceptor agonists. In the same rats, Pb affected the cyclic adenosine 3′-5′-monophosphate (cAMP)-dependent intracellular pathways that regulate availability of free calcium (Ca2+) for the contractile processes in both myocardium and vascular myocells.
KeywordsSympathetic Hyperactivity Contractile Process IFFA Credo Chronic Lead Exposure Cardiac Inotropism
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