Background. Angiotensin II stimulates synthesis and deposition of collagen and might contribute to the vascular and cardiac dysfunction associated with arterial hypertension. Insulin attenuates angiotensin II-induced responses of intracellular Ca2+ concentration ([Ca2+]) in many cell types but this effect is less in insulin-resistant states. The mechanisms of the interaction between insulin and angiotensin II are still not known. Objective. To characterize the effects of angiotensin II on intracellular [Ca2+] and the effects of insulin on the angiotensin II-induced response of intracellular [Ca2+] in human skin fibroblasts. Methods. Spectrofluorophotometric measurements of intracellular [Ca2+] in monolayers of cultured human skin fibroblasts from 15 normotensive patients were performed using Fura-2 at 510 nm emission with excitation wavelengths of 340 and 380 nm. Results. Basal intracellular [Ca2+] in quiescent (24 h serum-deprived) human fibroblasts was 75 ± 3 nmol/l (n = 20). Administration of angiotensin II elevated intracellular [Ca2+] dose-dependently with a concentration for half-maximal effect of 20 nmol/l. Administration of 100 nmol/l angiotensin II stimulated a rapid and transient increase in intracellular [Ca2+] (from 75 ± 3 to 130 ± 2 nmol/l, n = 20). Removal of extracellular calcium did not change peak intracellular [Ca2+], but it did reduce the time to recovery of [Ca2+] (from 64 ± 4 to 48 ± 2 s, n = 10, P < 0.01), suggesting that an angiotensin II-induced transmembrane calcium influx had occurred. This hypothesis was confirmed by quenching studies with manganese. The angiotensin II-induced changes in intracellular [Ca2+] were completely blocked by administration of 100 nmol/l of the angiotensin II type 1 receptor inhibitor losartan but not by administration of 100 nmol/l of the angiotensin II type 2 receptor blocker CGP42112A. Acute (20 min) exposure to 100 nmol/l insulin did not alter basal intracellular [Ca2+] in quiescent fibroblasts, but significantly blunted angiotensin II-stimulated peak of [Ca2+] (to 101 ± 3 nmol/l, P < 0.01, n = 18) and delayed recovery of [Ca2+] (to 99 ± 5 s, P < 0.01). The inhibitory effect of insulin was observed both with and without extracellular Ca2+. Conclusions. Our results demonstrate that administration of angiotensin II increases intracellular [Ca2+] in human skin fibroblasts by release of Ca2+ from intracellular Ca2+ stores and by influx of Ca2+ and that administration of insulin attenuates the response of [Ca2+] to angiotensin II but prolongs the time to recovery of [Ca2+].

Ceolotto, G., Pessina, A., Iori, E., Monari, A., Trevisan, R., Winkleswski, P., et al. (1998). Modulatory effect of insulin on release of calcium from human fibroblasts by angiotensin II. JOURNAL OF HYPERTENSION, 16(4), 487-493 [10.1097/00004872-199816040-00010].

Modulatory effect of insulin on release of calcium from human fibroblasts by angiotensin II

Trevisan R;
1998

Abstract

Background. Angiotensin II stimulates synthesis and deposition of collagen and might contribute to the vascular and cardiac dysfunction associated with arterial hypertension. Insulin attenuates angiotensin II-induced responses of intracellular Ca2+ concentration ([Ca2+]) in many cell types but this effect is less in insulin-resistant states. The mechanisms of the interaction between insulin and angiotensin II are still not known. Objective. To characterize the effects of angiotensin II on intracellular [Ca2+] and the effects of insulin on the angiotensin II-induced response of intracellular [Ca2+] in human skin fibroblasts. Methods. Spectrofluorophotometric measurements of intracellular [Ca2+] in monolayers of cultured human skin fibroblasts from 15 normotensive patients were performed using Fura-2 at 510 nm emission with excitation wavelengths of 340 and 380 nm. Results. Basal intracellular [Ca2+] in quiescent (24 h serum-deprived) human fibroblasts was 75 ± 3 nmol/l (n = 20). Administration of angiotensin II elevated intracellular [Ca2+] dose-dependently with a concentration for half-maximal effect of 20 nmol/l. Administration of 100 nmol/l angiotensin II stimulated a rapid and transient increase in intracellular [Ca2+] (from 75 ± 3 to 130 ± 2 nmol/l, n = 20). Removal of extracellular calcium did not change peak intracellular [Ca2+], but it did reduce the time to recovery of [Ca2+] (from 64 ± 4 to 48 ± 2 s, n = 10, P < 0.01), suggesting that an angiotensin II-induced transmembrane calcium influx had occurred. This hypothesis was confirmed by quenching studies with manganese. The angiotensin II-induced changes in intracellular [Ca2+] were completely blocked by administration of 100 nmol/l of the angiotensin II type 1 receptor inhibitor losartan but not by administration of 100 nmol/l of the angiotensin II type 2 receptor blocker CGP42112A. Acute (20 min) exposure to 100 nmol/l insulin did not alter basal intracellular [Ca2+] in quiescent fibroblasts, but significantly blunted angiotensin II-stimulated peak of [Ca2+] (to 101 ± 3 nmol/l, P < 0.01, n = 18) and delayed recovery of [Ca2+] (to 99 ± 5 s, P < 0.01). The inhibitory effect of insulin was observed both with and without extracellular Ca2+. Conclusions. Our results demonstrate that administration of angiotensin II increases intracellular [Ca2+] in human skin fibroblasts by release of Ca2+ from intracellular Ca2+ stores and by influx of Ca2+ and that administration of insulin attenuates the response of [Ca2+] to angiotensin II but prolongs the time to recovery of [Ca2+].
Articolo in rivista - Articolo scientifico
Angiotensin II; Fibroblasts; Genistein; Insulin; Intracellular calcium; Intracellular signalling; Losartan;
English
487
493
7
Ceolotto, G., Pessina, A., Iori, E., Monari, A., Trevisan, R., Winkleswski, P., et al. (1998). Modulatory effect of insulin on release of calcium from human fibroblasts by angiotensin II. JOURNAL OF HYPERTENSION, 16(4), 487-493 [10.1097/00004872-199816040-00010].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/368325
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