Abstract
The effects of the beta-adrenoceptor agonist isoprenaline and cyclic AMP (cAMP) on cytosolic free Ca2+ ([Ca2+]i) were studied in the single guinea-pig hepatocyte. In common with InsP3-dependent agonists such as noradrenaline or angiotensin II, isoprenaline (0.5-10 microM) and cAMP (50-100 mM, perfused into the cell via the patch-pipette), were able to generate fast and slow fluctuations of [Ca2+]i. Responses to isoprenaline and cAMP also were observed in the absence of external Ca2+. Isoprenaline-evoked [Ca2+]i rises were not blocked by the intracellular perfusion of heparin, suggesting that these fluctuations are independent of the binding of InsP3 to its receptor.
MeSH terms
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Angiotensin II / pharmacology
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Animals
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Calcium / metabolism*
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Cyclic AMP / pharmacology*
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Cytosol / metabolism
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Guinea Pigs
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Heparin / pharmacology
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Inositol Phosphates / metabolism
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Isoproterenol / pharmacology
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Liver / drug effects
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Liver / metabolism*
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Norepinephrine / pharmacology
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Potassium Channels / drug effects
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Potassium Channels / physiology
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Receptors, Adrenergic, alpha / drug effects
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Receptors, Adrenergic, alpha / physiology
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Receptors, Adrenergic, beta / drug effects
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Receptors, Adrenergic, beta / physiology
Substances
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Inositol Phosphates
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Potassium Channels
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Receptors, Adrenergic, alpha
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Receptors, Adrenergic, beta
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Angiotensin II
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Heparin
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Cyclic AMP
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Isoproterenol
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Calcium
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Norepinephrine