[Genetic abnormalities in cultured cutaneous fibroblasts in SHR rats]

Skin fibroblasts were isolated from newborn spontaneously hypertensive rats (SHR) and Wistar-Kyoto normotensive rats (WKY) to study their cell growth and reactivity in culture. SHR fibroblasts exhibited an enhanced growth rate in presence of 10 per cent fetal calf serum and a marked increase in 3H thymidine incorporation compared to WKY cells, when confluent quiescent fibroblasts were stimulated by 2, 5, 10 or 15 per cent serum as well as by 10 ng/ml EGF. Inositol phosphate formation determined by exchange chromatography in presence of 20 mM LiC1, was stimulated by serum, 1 microM angiotensin II, I microM bradykinin and 0.1 microM vasopressin in both type of cells labelled with 3H myoinositol. Significantly higher levels were produced in SHR cells by angiotensin II, serum and bradykinin compared to WKY fibroblasts. No difference between the two cell groups was observed with vasopressin. The intracellular pH (pHi) of isolated SHR and WKY fibroblasts was measured in bicarbonate-free medium using the fluorescent dye BCECF. The identical pHi values (7.03 +/- 0.10, n = 5 and 7.04 +/- 0.07, n = 6 for WKY and SHR respectively agree with an absence of Na+/H+ antiport activation in unstimulated cells. This study allows to conclude that skin fibroblasts isolated from newborn SHR, similarly to vascular smooth muscle cells, exhibit an hyperresponsiveness to serum, EGF and angiotensin II. These results demonstrate the presence of an intrinsic cellular developing capacity.