Anesthesiology
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Comparative Study
Left ventricular mechanical consequences of dihydropyridine calcium channel modulation in conscious and anesthetized chronically instrumented dogs.
Volatile anesthetics depress left ventricular contractile function by altering voltage-dependent slow calcium (Ca2+) channel activity in the sarcolemmal membrane. This investigation examined the left ventricular systolic and diastolic mechanical effects of the dihydropyridine Ca2+ channel antagonist nifedipine and agonist Bay k 8644 (Bay k) in dogs in the conscious state and during anesthesia. ⋯ Nifedipine caused direct negative inotropic actions in conscious and anesthetized dogs and worsened volatile anesthetic-induced negative lusitropic effects. Bay k improved left ventricular systolic and diastolic function in the conscious state. Bay k also improved contractility during anesthesia; however, Bay k only partially reversed volatile anesthetic-induced abnormalities in indexes of left ventricular diastolic function in dogs during autonomic nervous system blockade.