GROWTH-PROPERTIES AND RECEPTOR EXPRESSION IN VASCULAR SMOOTH-MUSCLE CELLS FROM HYPERTENSIVE RATS

The objective of this study was to evaluate the growth properties and receptor expression in aorta-ring derived smooth muscle cells (SMCs) c ultured from control (WKY) and spontaneously hypertensive rats (SHR). SHR-SMCs exhibited a 3-4 day lag period before migrating. In addition, SHR-SMCs had a significantly higher growth rate, shorter population d oubling time and higher saturation density level characteristics that were retained at higher passage levels. beta-adrenergic and angiotensi n (All) receptors were measured using iodocyanopindolol (ICYP) and [H- 3]-AII, respectively. All receptor expression was similar in both WKY and SHR-SMC cultures. WKY-SMCs exhibited little ICYP binding (Bmax 8.2 7 +/- 2.0 fmol/mg) while SHR-SMC binding capacity was 8 fold higher (B max 65 +/- 9.2 fmol/mg). In addition, the responsiveness of the P-rece ptor, as assessed by adenylyl cyclase stimulation, was similar for WKY and SHR-SMCs. These data suggest that factors regulating SMC receptor expression in vitro are selective since All and adrenergic receptor d ensities exhibit different responses to hypertension.