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Titolo:
POTENT VASOCONSTRICTOR ACTIONS OF CYCLOPIAZONIC ACID AND THAPSIGARGINON FEMORAL ARTERIES FROM SPONTANEOUSLY HYPERTENSIVE RATS
Autore:
NOMURA Y; ASANO M; ITO K; UYAMA Y; IMAIZUMI Y; WATANABE M;
Indirizzi:
NAGOYA CITY UNIV,SCH MED,DEPT PHARMACOL NAGOYA AICHI 467 JAPAN NAGOYA CITY UNIV,SCH MED,DEPT PHARMACOL NAGOYA AICHI 467 JAPAN MIYAZAKI UNIV,FAC AGR,DEPT VET PHARMACOL MIYAZAKI 88921 JAPAN NAGOYA CITY UNIV,FAC PHARMACEUT SCI,DEPT CHEM PHARMACOL NAGOYA AICHI 467 JAPAN
Titolo Testata:
British Journal of Pharmacology
fascicolo: 1, volume: 120, anno: 1997,
pagine: 65 - 73
SICI:
0007-1188(1997)120:1<65:PVAOCA>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
VASCULAR SMOOTH-MUSCLE; SUPERFICIAL BUFFER BARRIER; CYTOSOLIC FREE CALCIUM; SENSITIVE K+ CHANNELS; SARCOPLASMIC-RETICULUM; RESTING STATE; MECHANICAL-ACTIVITY; MYOGENIC TONE; INHIBITOR; AORTA;
Keywords:
SPONTANEOUSLY HYPERTENSIVE RATS (SHR); SARCOPLASMIC RETICULUM; CYCLOPIAZONIC ACID; THAPSIGARGIN; CYTOSOLIC CA2+ LEVEL; CA2+ INFLUX; VOLTAGE-DEPENDENT CA2+ CHANNELS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
46
Recensione:
Indirizzi per estratti:
Citazione:
Y. Nomura et al., "POTENT VASOCONSTRICTOR ACTIONS OF CYCLOPIAZONIC ACID AND THAPSIGARGINON FEMORAL ARTERIES FROM SPONTANEOUSLY HYPERTENSIVE RATS", British Journal of Pharmacology, 120(1), 1997, pp. 65-73

Abstract

1 The Ca2+ buffering function of sarcoplasmic reticulum (SR) in the resting state of arteries from spontaneously hypertensive rats (SHR) was examined. Differences in the effects of cyclopiazonic acid (CPA) andthapsigargin, agents which inhibit the Ca2+-ATPase of SR, on tension and cellular Ca2+ level were assessed in endothelium-denuded strips offemoral arteries from 13-week-old SHR and normotensive Wistar-Kyoto rats (WKY). 2 In resting strips preloaded with fura-PE3, the addition of CPA (10 mu M) or thapsigargin (100 nM) caused an elevation of cytosolic Ca2+ level ([Ca2+](i)) and a contraction. These responses were significantly greater in SHR than in WKY. 3 The addition of verapamil (3 mu M) to the resting strips caused a decrease in resting [Ca2+](i), which was significantly greater in SHR than in WKY. In SHR, but not in WKY, this decrease was accompanied by a relaxation from the resting tone, suggesting the maintenance of myogenic tone in the SHR artery. 4 Verapamil (3 mu M) abolished differences between SHR and WKY. The effects of verapamil were much greater on the contraction than on the [Ca2+](i). 5 The resting Ca2+ influx in arteries measured after a 5 min incubation of the artery with Ca-45 was not increased by CPA or thapsigargin in either SHR or WKY. The net Ca2+ entry measured after a 30 min incubation of the artery with Ca-45 was decreased by CPA or thapsigarginin both SHR and WKY. The resting Ca2+ influx was significantly higherin SHR than in WKY, and was decreased by nifedipine (100 nM) in the SHR artery, but was unchanged in the WKY artery. 6 The resting Ca-45 efflux from the artery was increased during the addition of CPA (10 mu M). This increase was less in SHR than in WKY. The resting Ca-45 effluxwas the same in SHR and WKY. 7 These results suggest that (1) the Ca2 influx via L-type voltage-dependent Ca2+ channels (VDCCs) was increased in the resting state of the SHR femoral artery, (2) the greater part of the increased Ca2+ influx was buffered by Ca2+ uptake into the SR and some Ca2+ reached the myofilaments resulting in the maintenance of the myogenic tone, and (3) therefore the functional elimination of SR by CPA or thapsigargin caused a large elevation of [Ca2+](i) and a potent contraction in this artery. During this process, the contraction was mainly due to the basal Ca2+ influx via L-type VDCCs. The present study also showed the existence of a relatively large compartment of[Ca2+](i) which does not contribute to the contraction during the addition of CPA or thapsigargin.

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Documento generato il 25/11/20 alle ore 17:53:44