+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Effect of twitch interval duration on the contractile function of subsequent twitches in isolated rat, rabbit, and dog myocardium under physiological conditions



Effect of twitch interval duration on the contractile function of subsequent twitches in isolated rat, rabbit, and dog myocardium under physiological conditions



Journal of Applied Physiology 111(4): 1159-1167



Many studies have shown that a change in stimulation frequency leads to altered contractility of the myocardium. However, it remains unclear what changes occur directly after a change in frequency and which ones are a result of the slow processes that lead to the altered homeostasis, which develops after a change in stimulation frequency. To distinguish the immediate from the slow responses, we assessed contractile function in two species that have distinctively different calcium (Ca(2+))-handling properties using a recently developed, randomized pacing protocol. In isolated dog and rat right ventricular trabeculae, twitch contractions at five different cycle lengths within the physiologic range of each species were randomized around a steady-state frequency. We found, in both species, that the duration of the cycle length just prior to the analyzed twitch (primary) positively correlated with the increased force of the analyzed twitch. In sharp contrast, the cycle lengths, one and two more removed from the analyzed twitch ("secondary" and "tertiary"), displayed a negative correlation with force of the analyzed twitch. In additional experiments, assessment of intracellular Ca(2+) transients in rabbit trabeculae revealed that diastolic Ca(2+) levels were closely correlated to contractile function outcome. The relative contribution of the primary cycle length was different between dog (51%) and rat (71%), whereas in neither species was a significant effect on relaxation time observed. With the use of randomized cycle lengths, we have distinguished the intrinsic response from the signaling-mediated effects of frequency-dependent activation on myofilament properties and Ca(2+) handling.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 052835496

Download citation: RISBibTeXText

PMID: 21778421

DOI: 10.1152/japplphysiol.01170.2010


Related references

Comparison of contractile function of isolated myocardium from FVB/N, C57BL/6, and SV129 mice under physiological conditions. Biophysical Journal 84(2 Part 2): 100a, 2003

Acute effects of iron on contractile function in isolated rabbit myocardium. Developmental Pharmacology and Therapeutics 7(1): 50-60, 1984

Influence of cyclosporine A on contractile function, calcium handling, and energetics in isolated human and rabbit myocardium. Cardiovascular Research 47(1): 99-107, 2000

Fatty acid metabolism and contractile function in the reperfused myocardium. Multinuclear NMR studies of isolated rabbit hearts. Circulation Research 68(3): 714-725, 1991

Effect of hyponatremia and frenolone on the contractile function of isolated myocardium. Fiziologicheskii Zhurnal 32(1): 39-43, 1986

Change in the contractile activity of the rabbit myocardium as a result of burn shock of different duration. Biulleten' Eksperimental'noi Biologii i Meditsiny 87(5): 402-405, 1979

Nitric oxide effects on myocardial function and force-interval relations: regulation of twitch duration. Journal of Molecular and Cellular Cardiology 31(12): 2077-2085, 1999

Relationships between peak force, action potential duration and stimulus interval in rabbit myocardium. Acta Physiologica Scandinavica 106(4): 395-409, 1979

Evaluation of the contractile function of the myocardium by the duration of the systolic phases. Evaluation of the contractile function of the myocardium by the duration of the systolic phases Ostenka sokratitel'noi funktsii miokarda po dlitel'nosti faz sistol 175p Illus, 1965

Effect of the rest interval on the contractile activity of the myocardium. Fiziologicheskii Zhurnal SSSR Imeni I. M. Sechenova 65(5): 707-713, 1979

The effect of heptanol on the electrical and contractile function of the isolated perfused rabbit heart. Journal of Physiology (Cambridge) 518P: 40P, 1999

The effect of heptanol on the electrical and contractile function of the isolated, perfused rabbit heart. Pflugers Archiv 440(2): 275-282, 2000

Dependence of hemodynamic changes and contractile function of the myocardium in patients with thyrotoxicosis on the severity and duration of the disease. Vrachebnoe Delo 11: 55-57, 1971

Effect of voltage clamp duration on force production of successive twitches in isolated ferret and guinea pig papillary muscle. Journal of Physiology (Cambridge) 381: 95P, 1986