Why the study?
Does phenylephrine affect L-type Ca2+ channel current differently in young versus neonatal rat myocytes?
Does phenylephrine affect L-type Ca2+ channel current differently in young versus neonatal rat myocytes?
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The coupling of alpha 1-adrenoceptors to Ca2+ channels appears to switch during development in rat hearts, with activation increasing Ca2+ current in neonatal but not young myocytes.
It has been reported in the literature that alpha 1-adrenoceptor activation in adult rat heart does not cause an increase in Ca2+ current but involves a decrease in I(t). This may explain in part the positive inotropic effect of alpha 1-adrenoceptor activation. In this study, the effect of phenylephrine, an alpha-adrenergic agonist, on L-type Ca2+ channel current was compared in young and neonatal rat myocytes. In the presence of propranolol, phenylephrine increased the Ca2+ current (reversed by prazosin) in neonatal but not in young rat myocytes suggesting that the coupling of the alpha 1-adrenoceptor to Ca2+ channels may switch during development.
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Liu et al. (1994) studied this question.
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