Plasmalemmal dihydropyridine receptors modify the function of subplasmalemmal inositol 1,4,5-trisphosphate receptors: a hypothesis.
Experimental observations on rat glomerulosa cells inspired a model which postulates that plasmalemmal dihydropyridine receptors are in juxtaposition and interaction with inositol 1,4,5-trisphosphate receptors in subplasmalemmal calciosomes. Activation of dihydropyridine receptors promotes the Ca2+ releasing effect of inositol 1,4,5-trisphosphate. The most important observations compatible with the model are the following: (1) angiotensin II does not influence Ca2+ influx during the peak phase of Ca2+ signal; (2) dihydropyridine drugs modify the initial peak of the Ca2+ signal induced by angiotensin II; (3) inhibitors of the dihydropyridine receptor reduce the initial Ca2+ signal also in the presence of 5 mM Ni2+, an inhibitor of voltage dependent Ca2+ influx; and (4) changes in extracellular K+ concentration within the physiological range also modify the cytoplasmic Ca2+ response to angiotensin II.
Spät
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Department of Physiology, Semmelweis University of Medicine, Budapest, Hungary.
Rohács
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Hunyady
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D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type; D002462:Cell Membrane / Q000737:chemistry; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007678:Kidney Glomerulus / Q000737:chemistry; D008954:Models, Biological; D009124:Muscle Proteins / Q000502:physiology*; D009532:Nickel / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D015398:Signal Transduction
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009124:Muscle Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D000804:Angiotensin II; C022838:nickel chloride; D009532:Nickel; D015544:Inositol 1,4,5-Trisphosphate; D011188:Potassium; D002118:Calcium