Alterations of calcium uptake in renovascular hypertensive rat aorta: functional assessment with thapsigargin.
1. The aim of this study was to test the hypothesis that impaired calcium (Ca2+) recycling by sarcoplasmic reticulum (SR) Ca2+-ATPase takes place in aortae from 1 kidney-1 clip (1K-1C) hypertensive rats. 2. The contractile response elicited when Ca2+ is released from the SR with phenylephrine and caffeine in Ca2+-free Krebs solution was greater in 1K-1C than in 1K rat aorta. In the arteries submitted to intracellular Ca2+ store depletion and reloading, this response was not different between 1K-1C and 1K rat aortae. Thapsigargin decreased the phasic contractile responses to phenylephrine in 1K and 1K-1C rat aortae and increased the tone that developed during the refilling period in 1K-1C rat aortae. 3. Our data support the hypothesis that the 1K-1C rat aorta has defective intracellular Ca2+ regulation that may be implicated in an inadequate SR buffering ability.
Ceron
P I
PI
Laboratory of Pharmacology, College of Pharmaceutical Sciences, University of São Paulo, Ribeirão Preto, Brazil.
Bendhack
L M
LM
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005069:Evaluation Studies as Topic; D006978:Hypertension, Renovascular / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects
D004791:Enzyme Inhibitors; D012433:Ryanodine; D010656:Phenylephrine; D002110:Caffeine; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium