Related Experiment Video
Updated: Aug 20, 2026

Isolation of Microvascular Endothelial Tubes from Mouse Resistance Arteries
Published on: November 25, 2013
Wortmannin inhibits the myofilament Ca2+ sensitization induced by endothelin-1
1Department of Cardiovascular Pharmacology, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
Abstract:
Endothelin-1 induces a positive inotropic effect due to a combination of an increase in Ca2+ transients and myofilament Ca2+ sensitivity in rabbit ventricular myocardium. We carried out the experiments to examine the potential contribution of myosin light chain kinase to the Ca2+ sensitization induced by endothelin-1 by use of wortmannin that inhibits myosin light chain kinase at high concentrations (IC50=200 nM). Wortmannin at 3 microM suppressed the basal force of contraction, but did not affect the positive inotropic effect mediated by beta-adrenoceptors. Wortmannin at 1 and 3 microM markedly inhibited the positive inotropic effect of endothelin-1, but did not affect the increase in Ca2+ transients elicited by endothelin-1. The present findings imply that the increase in myofilament Ca2+ sensitivity induced by endothelin-1 may be in part due to activation of myosin light chain kinase in rabbit ventricular myocardium.
Related Concept Videos
Nitric Oxide Signaling Pathway
Nondepolarizing (Competitive) Neuromuscular Blockers: Mechanism of Action
Competitive antagonists prevent acetylcholine from binding to its receptor, inhibiting membrane depolarization. Without conformational changes or intrinsic...
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...
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,...
Regulation of Angiogenesis and Blood Supply
Ligand-Gated Ion Channel Receptor: Gating Mechanism

