Related Experiment Video
Updated: Aug 1, 2026

Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
Published on: September 22, 2011
Effects of captopril and enalapril on intracellular Ca2+ in vascular smooth muscle cell
Aim:
To determine whether angiotensin-converting enzyme inhibitors can affect Ca2+ handling in cultured aortic smooth muscle cells (ASMC) directly.
Methods:
Cultured ASMC derived from rat aorta were loaded with the intracellular Ca2+ ([Ca]2+i) fluorescent indicator Fura 2-AM and digital image processing technique was used.
Results:
Resting [Ca2+]i was greater in ASMC from SHR vs WKY (P < 0.01). KCl-, norepinephrine (NE)-, and angiotensin II (Ang)-induced [Ca2+]i increases were enhanced in ASMC of SHR vs WKY (220 +/- 6, 212 +/- 8, and 215 +/- 14 vs 199 +/- 6, 202 +/- 7, and 195 +/- 7 nmol.L-1, respectively). Captopril (Cap) and enalapril (Ena) had no inhibitory effect on KCl-, NE-, and Ang-induced [Ca2+]i increases in ASMC of WKY. Cap and Ena inhibited KCl-, NE-, and Ang-increased [Ca2+]i in ASMC of SHR (210 +/- 7, 194 +/- 6, and 201 +/- 6 nmol.L-1, respectively). Ena and nifedipine similarly decreased KCl-, NE-, and Ang-increased [Ca2+]i.
Conclusion:
Cap blocked KCl-, NE-, and Ang-increased ([Ca2+]i) via a voltage-dependent Ca2+ channel of which function and specificity was altered in ASMC of SHR.
Related Concept Videos
Feedback Regulation of Calcium Concentration
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
Heart Failure Drugs: Inhibitors of Renin-Angiotensin System
Autoregulation of Blood Flow
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.

