Protein kinase C translocation in intact vascular smooth muscle strips.
Using intact muscle strips from the bovine carotid artery, the time course of translocation of protein kinase C (PKC) from the cytosol to the membrane fraction was measured in response to various agonists that induce contractile responses. PKC activity was assessed by Ca2+/phospholipid-dependent phosphorylation of histone. Exposure of the muscle strips to phorbol ester (12-deoxyphorbol 13-isobutyrate) induced a rapid and sustained translocation of PKC from the cytosol to the membrane fraction, and a slowly developing but sustained contractile response. Histamine induced a comparable initial translocation of PKC to the membrane which then decreased somewhat to a stable plateau significantly above basal values. Histamine also led to a rapid and sustained increase in tension. Angiotensin I, which caused a rapid but transient contraction, induced a rapid initial translocation of PKC to the membrane. The membrane-associated PKC then declined to a stable plateau significantly lower than that seen after a histamine-induced response, and only slightly above the basal value. Endothelin, which induced a sustained contraction, caused a sustained translocation of PKC from the cytosol to the membrane. In contrast, although exposure to 35 mM-KCl induced a rapid and sustained contraction, it caused only a transient translocation of PKC; the membrane-associated PKC returned to its basal value within 20 min. These results demonstrate that PKC in intact smooth muscle can be rapidly translocated to the membrane and remains membrane-bound during sustained phorbol ester- or agonist-induced contractions, but that such a sustained translocation of PKC does not occur during prolonged stimulation with KCl.
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510.
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Haller
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JI
Smallwood
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Rasmussen
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002339:Carotid Arteries; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D016232:Endothelins; D004730:Endothelium, Vascular / Q000502:physiology; D006632:Histamine / Q000494:pharmacology; D007700:Kinetics; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000502:physiology; D010455:Peptides / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*
D016232:Endothelins; D010455:Peptides; D010703:Phorbol Esters; D000804:Angiotensin II; C039067:12-deoxyphorbol 13-isobutyrate; D011189:Potassium Chloride; D006632:Histamine; D011493:Protein Kinase C