Membrane potential controls calcium entry into descending vasa recta pericytes.
We tested the hypothesis that constriction of descending vasa recta (DVR) is mediated by voltage-gated calcium entry. K(+) channel blockade with BaCl(2) (1 mM) or TEACl (30 mM) depolarized DVR smooth muscle/pericytes and constricted in vitro-perfused vessels. Pericyte depolarization by 100 mM extracellular KCl constricted DVR and increased pericyte intracellular Ca(2+) ([Ca(2+)](i)). The K(ATP) channel opener pinacidil (10(-7)-10(-4) M) hyperpolarized resting pericytes, repolarized pericytes previously depolarized by ANG II (10(-8) M), and vasodilated DVR. The DVR vasodilator bradykinin (10(-7) M) also reversed ANG II depolarization. The L-type Ca(2+) channel blocker diltiazem vasodilated ANG II (10(-8) M)- or KCl (100 mM)-preconstricted DVR, and the L-type agonist BayK 8644 constricted DVR. The plateau phase of the pericyte [Ca(2+)](i) response to ANG II was inhibited by diltiazem. These data support the conclusion that DVR vasoreactivity is controlled through variation of membrane potential and voltage-gated Ca(2+) entry into the pericyte cytoplasm.
Zhang
Zhong
Z
Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA.
Rhinehart
Kristie
K
Pallone
Thomas L
TL
D000818:Animals; D001808:Blood Vessels / Q000187:drug effects / Q000502:physiology; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000098:blood supply* / Q000166:cytology / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D018408:Patch-Clamp Techniques; D020286:Pericytes / Q000502:physiology*; D020110:Pinacidil / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology
D020746:Calcium Channels, L-Type; D026902:Potassium Channel Blockers; D014665:Vasodilator Agents; D011189:Potassium Chloride; D020110:Pinacidil; D001920:Bradykinin; D002118:Calcium