Transforming growth factor β1 modulates angiotensin induced calcium influx in vascular smooth muscle

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Abstract
The modulatory effects of transforming growth factor β1 (TGF β1) on the angiotensin II (Ang II)‐induced increase in cytosolic free calcium concentration ([Ca2+]i) were investigated in vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and normotensive Wistar‐Kyoto rats (WKY). [Ca2+]i in VSMC was measured using the fluorescent dye fura‐2. When TGF β1 was applied 30 s prior to Ang II, the Ang II‐induced [Ca2+]i increase was significantly enhanced in VSMC from SHR (P < 0.05 compared to control), whereas after the preincubation with TGF β1 for 30 min, the Ang II‐induced [Ca2+]i increase was significantly reduced in VSMC from both strains. Using the manganese‐quenching technique, it was confirmed that short‐term exposure to TGF β1 enhanced the Ang II‐induced trans‐plasma‐membrane calcium influx in SHR. The inhibition of protein kinase C by calphostin C abolished the stimulatory effect of TGF β1 on the Ang II‐induced [Ca2+]i increase. It is concluded that TGF β1 modulates the Ang II‐induced calcium handling in VSMC.