Endogenous regulation of vascular tone

Most vasoconstrictors bind to G protein → ↑ intracellular Ca2+ → smooth muscle contraction (by graded depolarisation)

Vasoconstricting Agents Vasodilating Agents
Endothelin-1 Nitric oxide
Thromboxane A2 Prostacyclin/prostaglandins
Angiotensin II Beta-agonists
Noradrenaline (alpha 1-receptors) Calcium-channel blockers
Bradykinin

Endothelin

Stimulus: hypoxia, ATII, ADH, noradrenaline