The platelet-derived growth factor isomers, PDGF-AA, PDGF-AB and PDGF-BB, induce contraction of vascular smooth muscle cells by different intracellular mechanisms.

The effect of human recombinant platelet-derived growth factor (PDGF) isoforms, (r)PDGF-AA, PDGF-AB and PDGF-BB, on contractility of rat aortic rings as well as on intracellular free Ca2+ ([Ca2+]i), intracellular pHi (pHi) and thromboxane A2 (TXA2) formation in cultured vascular smooth muscle cells (VSMC) was examined. PDGF-BB behaved similar to PDGF-AB and both have features characteristic of conventional vasoconstrictor-agonists that directly increase [Ca2+]i, activate the Na+/H+ exchanger, stimulate the TXA2 formation, and induced contraction in VSMC whereas PDGF-AA induced contraction without increasing of [Ca2+]i, pHi, and TXA2 formation.