Characteristics of arterial myosin in experimental renal hypertension in the dog.

Abstract

We compared myosin samples isolated from iliac-femoral arteries of control and renal (stenosis) hypertensive dogs to determine the effects of increased blood pressure on the characteristics of the myosin. The ratio of 204-kd (SM-1) to 200 -kd (SM-2) myosin heavy chains was approximately 1:0.75 for myosin from the iliac-femoral artery of normotensive dogs. This was not altered significantly in response to hypertension. Both SM-1 and SM-2 myosin heavy chains cross-reacted with antibody against smooth muscle myosin on Western blot analysis. In addition to these heavy chains, purified myosin from both groups showed a very faint protein band slightly below the 200-kd myosin heavy chain on electrophoresis on a highly porous sodium dodecyl sulfate-polyacrylamide gel. This protein band cross-reacted with antibody against nonmuscle myosin but not with smooth muscle myosin antibody. The 20-and 17-kd light chains of myosin isolated from normotensive and hypertensive dogs gave similar results on isoelectric focusing. Peptide maps of tryptic digests of heavy chains revealed both quantitative and qualitative differences. The Ca "-activated myosin ATPase activity measured in high salt (0.5 mol/L KC1) was similar for myosin from both groups, whereas the potassium (ethylenedinitrilo)tetraacetic acid-stimulated ATPase of myosin from hypertensive animals was higher than that from normotensive animals. The actin-activated ATPase activities of the myosin from hypertensive animals was also higher than that of the myosin isolated from normotensive artery (0.11 ±0.007 and 0.213±0.008 fimo\ Pi per milligram per minute, respectively, for normotensive and hypertensive). These studies indicate that the structural and functional properties of myosin in a muscular artery are altered in hypertensive dogs. Adaptive changes in the vascular smooth muscle are observed with primary hypertension in humans and in spontaneously hypertensive rats.5 Increased thickness of the arterial media with a decrease in lumen diameter has been observed in a variety of hypertensive models.5 " 7 The increase in the wall thickness associated with hypertension is accompanied by an increase in smooth muscle mass. 7 The growth response of cells in the

Regional variation in myosin isoforms and phosphorylation at the resting tone in urinary bladder smooth muscle

“…Quantitation of heavy chain isoforms and Western blot analysis. The SM1 and SM2 myosin heavy chains were separated by slow electrophoresis of denatured protein on highly porous SDS-polyacrylamide gels (4.5%) as previously described (36). After having been stained with Coomassie blue, proteins were quantitated by scanning densitometry with a Bio-Rad GS-700 imaging densitometer.…”

Alteration in expression of myosin isoforms in detrusor smooth muscle following bladder outlet obstruction

“…The extracted muscle proteins present in the supernatant were separated from cell membrane and connective tissue fractions by centrifugation (13,000 g for 20 min). The MHCs SM1 and SM2 were separated by electrophoresis of the supernatant on large (16 ϫ 16 cm) 4.5% SDS-polyacrylamide slab gels (1 mm thick) as previously described (60). Coomassie brilliant blue-stained proteins were quantified by scanning densitometry of the gel using the Bio-Rad GS-700 imaging densitometer and Bio-Rad Quantity One program described above.…”

Regulation of actomyosin and contraction in smooth muscle

“…Studies on uterine smooth muscle indicate that the composition of the myosin isoforms is altered during hypertrophy [34]. We have demonstrated that the arterial myosin from normotensive and hypertensive dogs shows no difference in the composition of the SM1 and SM2 isoforms [53]. However, analysis of the peptides from myosin heavy chains by finger printing reveals quantitative and qualitative differences in arterial myosin from normotensive and hypertensive dogs [53].…”

“…We have demonstrated that the arterial myosin from normotensive and hypertensive dogs shows no difference in the composition of the SM1 and SM2 isoforms [53]. However, analysis of the peptides from myosin heavy chains by finger printing reveals quantitative and qualitative differences in arterial myosin from normotensive and hypertensive dogs [53]. The actin-activated ATPase activity of myosin isolated from arteries of hypertensive dogs is two-fold that of normals ( Table 1).…”