THE CORRELATION OF BLOOD-PRESSURE, AGE AND ENDOTHELIN-1 BINDING-SITESIN AORTIC SMOOTH-MUSCLE CELLS OF RATS

Spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), and Sprague-Dawl ey (SD) rats at the ages of 4, 8, 12, 16 and 24 weeks were used to exa mine the effects of age on the density of endothelin-1 (ET-1) binding sites in aortic smooth muscle cells and systolic blood pressure (SBP). The SEP of the 3 different rat strains was measured, and the maximum binding value (Bmax) and dissociation constant (Kd) of ET-1 binding si tes in smooth muscle cells of the thoracic aorta were determined. The results showed that the SEP and Bmax values of SHR, WKY and SD rats in creased with age; the SEP and Bmax value at each corresponding age wer e significantly higher in SHR than in WKY and SD rats, however, there was no significant difference between WKY and SD rats. The relationshi p of age vs SEP, age vs Bmax, and Bmax vs SEP showed significantly pos itive correlation in all 3 rat strains. The regression Line in the Bma x of endothelin binding sites against SEP in the 3 different rat strai ns presented a similar slope. These results indicate that SEP, which i ncreased with age, could be related to an increased density of ET-1 bi nding sites on vascular smooth muscle cells in these 3 different rat s trains.