Cardiovascular research
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Cardiovascular research · Oct 1999
Effects of the calcium channel antagonist mibefradil on haemodynamic parameters and myocardial Ca(2+)-handling in infarct-induced heart failure in rats.
Abnormal intracellular Ca(2+)-handling has been implicated in the pathogenesis of contractile dysfunction and arrhythmias in failing hearts. Calcium channel antagonists (CCA) have been proposed for the prevention of cardiac events after myocardial infarction (MI). Recent studies suggest that the blockade of T-type Ca(2+)-channels induced a heart rate reduction without negative inotropic effects. We investigated the effects of the preferentially T-channel blocking CCA, mibefradil, on haemodynamic parameters and intramyocardial Ca(2+)-handling and contractility in the early and late period after MI. ⋯ We conclude, that mibefradil improves cardiac function, protects the myocardium against ischemia-induced Ca(2+)-overload and increases beta-adrenergic responsiveness in chronically failing rat hearts.
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Cardiovascular research · Oct 1999
Pressor and mesenteric arterial hyporesponsiveness to angiotensin II is an early event in haemorrhagic hypotension in anaesthetised rats.
Vascular responsiveness to vasoconstrictors is known to be attenuated in haemorrhagic shock. In this study we assessed the temporal development and the underlying mechanisms of haemorrhage-induced vascular hyporeactivity to pressor agents. ⋯ Systemic pressor responsiveness and mesenteric arterial reactivity to endogenous and exogenous angiotensin II is selectively impaired at an early stage of haemorrhagic hypotension. This phenomenon partially involves NO and is not related to ATP-sensitive K+ channels.