Exercise training attenuates ageing-induced BKCa channel downregulation in rat coronary arteries

Sulayma Albarwani, Sultan Al-Siyabi, Hajar Baomar, Mohammed O. Hassan

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Physical inactivity and ageing are widely recognized as risk factors for development of coronary artery disease. One of the characteristic changes that occurs in aged coronary artery is downregulation of their large-conductance voltage- and calcium-activated K+ (BKCa) channels. In this study, we investigated the effects of moderate exercise training (ET) on the activity of BKCa channels in coronary arteries of aged rats. Old Fischer 344 rats (23-26 months old) were randomly assigned to sedentary (O-SED, n = 24) or exercise-trained groups (O-ET, n = 28). The O-ET rats underwent a progressive treadmill exercise-training programme for 60 min day-1, 5 days week-1 for 12 weeks. Young animals were used for comparison. Coronary arteries were mounted on a wire myograph, and contractions in response to 1, 10, 30, 50 and 100 nmol l-1 iberiotoxin were compared. Iberiotoxin (100 nmol l-1) contracted coronary arteries of young, O-SED and O-ET rats by 115 ± 14, 36 ± 5.6 and 61 ± 5% of 5-hydroxytryptamine-induced contractions, respectively. Patch-clamp studies revealed a larger magnitude of BKCa current in young (104 ± 15.6 pA pF-1) compared with O-ET (44 ± 9 pA pF-1) and least in O-SED coronary smooth muscle cells (8.6 ± 2 pA pF -1). Western immunoblotting was performed to study expression levels of BKCa channel proteins. The α and β1 subunits of the BKCa channel were reduced by 40 ± 3.5 and 30 ± 2.6%, respectively, in coronary arteries of old compared with young rats, and ET attenuated this reduction in expression level to 28 ± 2 and 12 ± 4%, respectively. Our results showed that ageing was associated with a reduction in BKCa channels, and ET partly reversed this reduction. We conclude that low-intensity ET may be beneficial in restoring age-related decline in coronary vasodilatory properties mediated by BKCa channels.

Original languageEnglish
Pages (from-to)746-755
Number of pages10
JournalExperimental Physiology
Volume95
Issue number6
DOIs
Publication statusPublished - Jun 2010

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Coronary Vessels
Down-Regulation
Exercise
Calcium-Activated Potassium Channels
Inbred F344 Rats
Smooth Muscle Myocytes
Coronary Artery Disease
Serotonin
Teaching
Western Blotting
Education
Proteins

ASJC Scopus subject areas

  • Physiology

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Exercise training attenuates ageing-induced BKCa channel downregulation in rat coronary arteries. / Albarwani, Sulayma; Al-Siyabi, Sultan; Baomar, Hajar; Hassan, Mohammed O.

In: Experimental Physiology, Vol. 95, No. 6, 06.2010, p. 746-755.

Research output: Contribution to journalArticle

Albarwani, Sulayma ; Al-Siyabi, Sultan ; Baomar, Hajar ; Hassan, Mohammed O. / Exercise training attenuates ageing-induced BKCa channel downregulation in rat coronary arteries. In: Experimental Physiology. 2010 ; Vol. 95, No. 6. pp. 746-755.
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abstract = "Physical inactivity and ageing are widely recognized as risk factors for development of coronary artery disease. One of the characteristic changes that occurs in aged coronary artery is downregulation of their large-conductance voltage- and calcium-activated K+ (BKCa) channels. In this study, we investigated the effects of moderate exercise training (ET) on the activity of BKCa channels in coronary arteries of aged rats. Old Fischer 344 rats (23-26 months old) were randomly assigned to sedentary (O-SED, n = 24) or exercise-trained groups (O-ET, n = 28). The O-ET rats underwent a progressive treadmill exercise-training programme for 60 min day-1, 5 days week-1 for 12 weeks. Young animals were used for comparison. Coronary arteries were mounted on a wire myograph, and contractions in response to 1, 10, 30, 50 and 100 nmol l-1 iberiotoxin were compared. Iberiotoxin (100 nmol l-1) contracted coronary arteries of young, O-SED and O-ET rats by 115 ± 14, 36 ± 5.6 and 61 ± 5{\%} of 5-hydroxytryptamine-induced contractions, respectively. Patch-clamp studies revealed a larger magnitude of BKCa current in young (104 ± 15.6 pA pF-1) compared with O-ET (44 ± 9 pA pF-1) and least in O-SED coronary smooth muscle cells (8.6 ± 2 pA pF -1). Western immunoblotting was performed to study expression levels of BKCa channel proteins. The α and β1 subunits of the BKCa channel were reduced by 40 ± 3.5 and 30 ± 2.6{\%}, respectively, in coronary arteries of old compared with young rats, and ET attenuated this reduction in expression level to 28 ± 2 and 12 ± 4{\%}, respectively. Our results showed that ageing was associated with a reduction in BKCa channels, and ET partly reversed this reduction. We conclude that low-intensity ET may be beneficial in restoring age-related decline in coronary vasodilatory properties mediated by BKCa channels.",
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