Contribution of sarcoplasmic reticulum calcium uptake and L-type calcium channels to altered vascular responsiveness in the aorta of renal hypertensive rats.
This study examined whether alterations in intracellular or extracellular Ca2+ mobilization were related to differences in caffeine and phenylephrine (PHE)-induced contractions between two-kidney. one-clip hypertensive (2K-1C) and normotensive (2K) rat aortas. After depletion and reloading of intracellular Ca2+ stores, caffeine and PHE-induced contractions in Ca2+-free solution were increased in 2K-1C. Thapsigargin reduced the contraction to caffeine in 2K-1C and 2K with similar sensitivity. PHE-induced contraction in 1.6-mM Ca2+ solution was decreased in 2K-1C, and nifedipine was less effective in lowering this response. The responsiveness to extracellular Ca2+ was decreased in 2K-1C hypertensive rat aortas. Our results indicate an increased intracellular Ca2+ stores that are not related to alteration in Ca2+-ATPase function and a lower contribution of L-type channels to the contraction of 2K-1C aortas.
Callera
G E
GE
Laboratory of Pharmacology, College of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, SP, Brazil.
Bendhack
L M
LM
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D006977:Hypertension, Renal / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects
D020746:Calcium Channels, L-Type; D010656:Phenylephrine; D002110:Caffeine; D011189:Potassium Chloride; D019284:Thapsigargin; D009543:Nifedipine; D002118:Calcium