Figure 5 .
The exogenous ET-1 acts via ETRA receptors to cause [Ca2+]i mobilization in SMCs embedded in renal vascular walls. A) Two-photon microphotograph of the renal microvessel before and after ET-1 application in the presence of ETRB antagonist (BQ788). Shown are fluorescence and the corresponding transmitted light image. Changes in the vessel diameter are visible in transmitted light during the application of ET-1 and the corresponding mobilization of [Ca2+]i in SMCs. Scale bar, 40 µm. B) Summary of the response to the ET-1 application in vessels treated by ETRA (BQ123) or ETRB (BQ788) antagonists. Total [Ca2+]i, calculated as integral of ET-1–mediated transient, indicates a significant attenuation of the calcium response during the ETRA blockade (n ≥ 4 vessels; n ≥ 4 rats for each group). *P < 0.05 (ANOVA).