Key Points
- To investigate the role of protein kinase C in arterial smooth muscle contraction using the activator 12-o-tetradecanoylphorbol-13-acetate (TPA).
- Tested the effects of TPA (0.1 µM) and phosphatidylserine on potassium- and calcium-induced contractions in intact and chemically skinned rabbit mesenteric artery preparations.
- Measured intracellular calcium transients using quin-2 fluorescence in dispersed cell suspensions from porcine coronary arteries and estimated calcium stores via caffeine response.
- TPA displayed dual actions, enhancing contractions at low calcium concentrations (0.1–0.3 µM) and during 39 mM potassium exposure, but inhibiting contractions at high calcium levels (1–10 µM) and 128 mM potassium.
- TPA did not alter intracellular calcium storage or high-potassium-induced calcium transients, indicating direct action on contractile regulatory proteins.
Structured PICO
PPopulationIntact and skinned smooth muscle preparations of the rabbit mesenteric artery, and dispersed cell suspensions prepared from the porcine coronary artery
IIntervention12-o-tetradecanoylphorbol-13-acetate (TPA) (0.1 microM), with or without phosphatidylserine (PS)
OOutcomeMechanical response (contraction amplitude) and Ca2+ transientssurrogate
TPA demonstrates dual, calcium-dependent effects on vascular smooth muscle contractile machinery, indicating that protein kinase C activation primarily enhances contraction.