Effect of cyclic stretch on alpha-subunit mRNA expression of Na+-K+-ATPase in aortic smooth muscle cells.
We previously demonstrated that protein expression of both alpha(1)- and alpha(2)-catalytic subunits of the Na+-K+-ATPase is elevated after a 2- to 4-day chronic cyclic stretch regimen in cultured aortic smooth muscle cells (ASMC). In the present study, we investigated whether cyclic stretch affects mRNA expression of the alpha-isoforms of the Na+-K+-ATPase. Using a stretch apparatus, rat ASMC were cyclically stretched 10 or 20% of their length for 1, 3, or 6 h. alpha-Isoform mRNA levels were measured using Northern analysis. A 3-h 10% stretch had no significant affect on mRNA expression for either isoform, but a 20% stretch increased mRNA of both isoforms approximately twofold. Whereas a 6-h 20% stretch increased alpha(1) mRNA by 3.3-fold, alpha(2) was not affected any further. Actinomycin D blocked the stretch-induced stimulation of mRNA expression of both alpha-subunits. In conclusion, cyclic stretch stimulates the mRNA expression of both alpha(1)- and alpha(2)-subunits of Na+-K+-ATPase. The sensitivity of the two genes to the degree and duration of stretch is different. The stretch-induced increase of mRNA may be a result of increased transcription.
Sevieux
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N
Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
Alam
J
J
Songu-Mize
E
E
D000818:Animals; D001011:Aorta / Q000166:cytology; D015152:Blotting, Northern; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000378:metabolism; D013314:Stress, Mechanical; D014158:Transcription, Genetic / Q000502:physiology
D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D003609:Dactinomycin; D005682:Gadolinium; D000254:Sodium-Potassium-Exchanging ATPase