Effects of gadolinium on length-dependent force in guinea-pig papillary muscle

The degree to which stretch-activated channels operate during physiological length changes in multicellular heart preparations, or how much the channels could contribute to length-dependent activation, is not known. We studied the relationship between muscle length and contractile force in guinea-pi...

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Veröffentlicht in:Experimental physiology 1994-03, Vol.79 (2), p.249-255
Hauptverfasser: Lab, MJ, Zhou, BY, Spencer, CI, Horner, SM, Seed, WA
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Sprache:eng
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Zusammenfassung:The degree to which stretch-activated channels operate during physiological length changes in multicellular heart preparations, or how much the channels could contribute to length-dependent activation, is not known. We studied the relationship between muscle length and contractile force in guinea-pig papillary muscles superfused with gadolinium chloride (10 microM), a stretch-activated channel blocker, and compared the effects to those with nifedipine (0.25 microM), a calcium channel blocker. Gadolinium reduced contractile force statistically significantly more at the longer muscle lengths than at the short muscle lengths. This did not apply with nifedipine, although a marginally greater effect at longer lengths was perceptible. The results can only partly be explained by gadolinium having a non-specific action via the calcium channel, or Na(+)-Ca2+ exchange, and are consistent with the possibility that stretch-activated channels contribute to length-dependent activation in cardiac muscle, and thus to 'Starling's Law of the Heart'.
ISSN:0958-0670
1469-445X
DOI:10.1113/expphysiol.1994.sp003758