Expression of smooth muscle myosin heavy chain B in cardiac vessels of normotensive and hypertensive rats.
We investigated expression of the 5'-spliced isoform of smooth muscle myosin heavy chain (SM-MHC-B) in smooth muscle cells of cardiac vessels of the left ventricle of normotensive (Wistar-Kyoto) and spontaneously hypertensive rats of the stroke-prone strain by immunofluorescence microscopy. In parallel, liver and bladder were studied for characterization of the nature of vessels expressing SM-MHC-B and for semiquantitative evaluation of its abundance. Smooth muscle cells were detected by staining with a monoclonal antibody specific for alpha-smooth muscle actin. Abundance of the SM-MHC-B isoform in these cells was evaluated by using an antibody raised against the seven-amino acid insert at the 25K/50K junction of the myosin head (a25K/50K) that specifically recognized SM-MHC-B. In the ventricle, a25K/50K immunoreactivity was observed in smooth muscle cells of precapillary arterioles but not in larger vessels or aorta. The a25K/50K immunoresponse of those vessels with the highest expression level of SM-MHC-B closely resembled the signal observed in the smooth muscle layer of urinary bladder known to preferentially express SM-MHC-B. Interestingly, in left ventricles of stroke-prone spontaneously hypertensive rats, there was a significantly reduced fraction of a25K/50K-positive precapillary arterioles compared with normotensive control rats.
Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
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Wetzel
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Lutsch
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Haase
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Ganten
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Morano
D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism / Q000473:pathology; D001160:Arterioles / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D002561:Cerebrovascular Disorders / Q000235:genetics; D003331:Coronary Vessels / Q000378:metabolism* / Q000473:pathology; D004198:Disease Susceptibility; D005786:Gene Expression Regulation; D006352:Heart Ventricles; D006973:Hypertension / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008099:Liver / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D018995:Myosin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics; D009928:Organ Specificity; D012326:RNA Splicing; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D001743:Urinary Bladder / Q000378:metabolism
D018995:Myosin Heavy Chains