Aortas isolated from sinoaortic-denervated rats exhibit rhythmic contractions that are regulated by pharmacologically distinct calcium sources.
Sinoaortic denervation is characterized by arterial pressure lability, without sustained hypertension. Aortas isolated from rats with sinoaortic denervation present rhythmic contractions. We studied the participation of distinct Ca(2+) sources in the maintenance of the oscillations. Three days after the surgeries, aortic rings were placed in an organ chamber, and the incidence of aortas presenting rhythmic contractions was measured. Specific drugs were employed to analyse the participation of the Ca(2+) released from the sarcoplasmic reticulum [2-APB (diphenylborinic acid 2-aminoethyl ester), thapsigargin and ryanodine] and external Ca(2+) entry [Bay K 8644, verapamil and DMB (dimethylbenzyl amiloride)] on the rhythmic contractions. Additionally, we verified the effects of chloride channel blocker NPPB [5-nitro-2-(3-phenylpropylamino)-benzoic acid] on the maintenance of the rhythmic contractions. Under phenylephrine stimulus, sinoaortic-denervated rat aortas exhibited rhythmic contractions in the frequency of 4.5 +/- 0.50 cycles/min. and an amplitude of 0.465 +/- 0.05 g. 2-APB, thapsigargin and ryanodine inhibited the rhythmic contractions. Bay K 8644 increased the oscillations, reaching maximum values with a concentration of 50 nM (18.5 +/- 2.5 cycles/min.). The rhythmic contractions were inhibiting by verapamil and Ca(2+)-free solution. DMB and NPPB did not alter the oscillations. In conclusion, we observed that aorta isolated from sinoaortic-denervated rats present rhythmic contractions. Moreover, drugs that impaired intracellular Ca(2+) release from sarcoplasmic reticulum interrupted the oscillations. The oscillations also depend on the extracellular Ca(2+) entry through L-type Ca(2+).
Rocha
Matheus L
ML
Department of Pharmacology, Faculty of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
Bendhack
Lusiane M
LM
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D017763:Autonomic Denervation; D001794:Blood Pressure / Q000187:drug effects; D001896:Boron Compounds / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000187:drug effects / Q000378:metabolism; D008297:Male; D049990:Membrane Transport Modulators / Q000494:pharmacology*; D009579:Nitrobenzoates / Q000494:pharmacology; D010507:Periodicity; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology; D019831:Sodium-Calcium Exchanger / Q000187:drug effects / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D001896:Boron Compounds; D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D018118:Chloride Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D049990:Membrane Transport Modulators; D009579:Nitrobenzoates; D019837:Ryanodine Receptor Calcium Release Channel; D026941:Sodium Channel Blockers; D019831:Sodium-Calcium Exchanger; D014662:Vasoconstrictor Agents; D012433:Ryanodine; D010656:Phenylephrine; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D019284:Thapsigargin; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000584:Amiloride; D014700:Verapamil; C109986:2-aminoethoxydiphenyl borate; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases