Key Points
- To determine how atrial natriuretic peptide affects agonist-induced contraction, calcium signaling, and myosin light chain phosphorylation in vascular smooth muscle.
- Treated isolated rabbit aortic smooth muscle strips with 10⁻⁷ M atrial natriuretic peptide either before or after administration of 5 × 10⁻⁸ M angiotensin II or 10⁻⁵ M histamine.
- Measured contractile responses, changes in intracellular free calcium concentrations, and the extent of myosin light chain phosphorylation.
- Preincubation with atrial natriuretic peptide inhibited contractile responses and myosin light chain phosphorylation induced by angiotensin II and histamine without altering agonist-evoked rises in intracellular calcium.
- Application of atrial natriuretic peptide to precontracted muscle strips triggered prompt muscle relaxation accompanied by rapid dephosphorylation of myosin light chains.
Structured PICO
PPopulationStrips of rabbit aorta smooth muscle
IInterventionAtrial natriuretic peptide (ANP) 10(-7) M
OOutcomeExtent of myosin light chain phosphorylation and contractile responsesurrogate
ANP induces vascular smooth muscle relaxation by uncoupling the initial agonist-induced Ca2+ transient from myosin light chain phosphorylation.