An hypothesis for the interpretation of the contractile response of vascular smooth muscle at the cellular level.
The long preservation and recovery of functional (contractile) properties in cultured aortic smooth muscle cells, even after replating or deep-frozen storage and the measurement of their responses are now technically settled issues. We could thus study extensively the responses of single cultured cells from rat thoracic aorta. Responses were elicited by the addition of KCl 40 mmol/L without or with a calcium blocker PN 200-100 (10(-6) mol/L); angiotensin II (10(-11)-10(-6) mol/L) without or with antagonist (losartan 10(-5) mol/L); or serotonin (10(-9)-10(-4) mol/L) without or with antagonist (naftidrofuryl 10(-5) mol/L). Results thus obtained enabled us to propose a new hypothesis for the interpretation of the contractile responses of an elastic vascular smooth muscle. The different maximal effects of different agonists result mainly from the different proportions of cells they can mobilize; the agonist concentration-contraction relationship is mainly due to the increase of the proportion of cells involved up to a maximal value typical of the agonist used. An antagonist primarily reduce the proportion of cells an agonist can mobilize. Some of the consequences of this hypothesis are briefly outlined.
Travo
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Centre de Recherches de Biochimie Macromoléculaire, UPR 9008 CNRS, U 249 INSERM, Université de Montpellier 1, France.
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Benel
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D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001013:Aorta, Thoracic / Q000166:cytology; D001713:Biphenyl Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D007093:Imidazoles / Q000494:pharmacology; D017275:Isradipine / Q000494:pharmacology; D019808:Losartan; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D013777:Tetrazoles / Q000494:pharmacology
D000889:Anti-Arrhythmia Agents; D001713:Biphenyl Compounds; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; D012701:Serotonin; D011189:Potassium Chloride; D019808:Losartan; D017275:Isradipine