Stimulation of collagen gel contraction by angiotensin II and III in cardiac fibroblasts

The aim of the present study was to investigate whether angiotensin II, angiotensin III or angiotensin II(2-8), angiotensin IV or angiotensin II(3-8) and angiotensin II(1-7), II(4-8), II(5-8) and II(1-4) could stimulate the collagen gel contraction in cardiac fibroblasts in serum-free conditions. Cardiac fibroblasts (from male adult Wistar rats) from passage 2 were cultured to confluency and incubated on a hydrated collagen gel, with and without these angiotensins, in a Dulbecco's Modified Eagle's Medium without fetal bovine serum for 1, 2 and 3 days. The area of the collagen gels embedded with cardiac fibroblasts was determined by a densitometric analysis. Collagen gel contraction was characterized by a decrease of the gel area. Angiotensin II stimulated dose-dependently the contraction of the collagen gel mediated by cardiac fibroblasts after 1, 2 and 3 days of incubation in a serum-free medium. Telmisartan completely blocked the angiotensin II-induced collagen contraction by cardiac fibroblasts. PD123,319 and des-Asp1-Ile8-angiotensin II had no effect on the angiotensin II-induced collagen contraction by cardiac fibroblasts. Angiotensin III also stimulated the contraction of collagen gel mediated by cardiac fibroblasts after 1, 2 or 3 days of incubation in a serum-free medium. des-Asp1-Ile8-angiotensin II, but also telmisartan, completely blocked the angiotensin III-induced collagen gel contraction by cardiac fibroblasts.des-Asp1-Ile8-angiotensin II had however no effect on the angiotensin II-induced collagen gel contraction by cardiac fibroblasts. Angiotensin IV and angiotensin II(4-8), (5-8), (1-7) and (1-4) did not affect the collagen gel contraction by cardiac fibroblasts. Addition of telmisartan, PD123,319 or des-Asp1-Ile8-angiotensin II alone dit not affect the collagen gel contraction by cardiac fibroblasts. Our data demonstrated that the effects of angiotensin II on the collagen gel contraction by cardiac fibroblasts in serum-free conditions were angiotensin II type 1 receptor mediated because they were abolished by the specific angiotensin II type 1 receptor antagonist telmisartan and not by PD 123,319 or des-Asp1-Ile8-angiotensin II, respectively an angiotensin II type 2 receptor antagonist and an angiotensin III antagonist. The angiotensin III-stimulated contraction of the collagen gel by cardiac fibroblasts was completely blocked by des-Asp1-Ile8-angiotensin II and by telmisartan.