Prolonged
vasoconstrictor-stimulated
phospholipase C activity can induce arterial constriction,
hypertension, and smooth muscle
hypertrophy/
hyperplasia.
Arrestin proteins are recruited by agonist-occupied
G protein-coupled receptors to terminate signaling and counteract changes in vascular tone. Here we determine whether the development of
hypertension affects
arrestin expression in resistance arteries and how such changes alter arterial contractile signaling and function. Arrestin2/3 expression was increased in mesenteric arteries of 12-wk-old spontaneously hypertensive rats (SHR) compared with normotensive Wistar-Kyoto (WKY) controls, while no differences in
arrestin expression were observed between 6-wk-old SHR and WKY animals. In mesenteric artery myography experiments, high extracellular K(+)-stimulated contractions were increased in both 6- and 12-wk-old SHR animals. Concentration-response experiments for
uridine 5'-triphosphate (
UTP) acting through P2Y receptors displayed a leftward shift in 12-wk, but not 6-wk-old animals. Desensitization of
UTP-stimulated vessel contractions was increased in 12-wk-old (but not 6-wk-old) SHR animals. Dual IP3/Ca(2+) imaging in mesenteric arterial cells showed that desensitization of
UTP and
endothelin-1 (ET1) responses was enhanced in 12-wk-old (but not 6-wk-old) SHR compared with WKY rats.
siRNA-mediated depletion of arrestin2 for
UTP and
arrestin3 for ET1, reversed the desensitization of PLC signaling. In conclusion, arrestin2 and 3 expression is elevated in resistance arteries during the emergence of the early hypertensive phenotype, which underlies an enhanced ability to desensitize
vasoconstrictor signaling and vessel contraction. Such regulatory changes may act to compensate for increased
vasoconstrictor-induced vessel contraction.