Pressure-induced hypertrophy of cat right ventricle. An evaluation with the force-interval relationship.
Year: 1977
Type: article
Abstract: We evaluated the force-interval relationship for papillary muscle isolated from two groups of cats, one sham-operated (control group), the other having undergone pulmonary artery constriction (hypertrophy group) 18.6 ± 2.9 weeks prior to sacrifice.The right ventricular free wall muscle mass and the peak systolic right ventricular pressure were significantly greater in the hypertrophy than in the control group.The peak force and maximum rate of rise of force (F max ) per cross-sectional area were not significantly different for the two groups.The qualitative features of the force-interval relationship, in particular postextrasystolic potentiation, were the same for both groups.There were quantitative differences between the groups, however.The amount of potentiation expressed, the ratio of F max of the potentiated to that of the previous regular contraction (i.e., the force-interval ratio), was significantly greater in the hypertrophied than in the control group.In both groups, the force-interval ratio was independent of muscle length, yet was altered by changing the inotropic state of the muscle (e.g., by alterations in calcium concentration).Increasing and decreasing the calcium concentration decreased and increased, respectively, the force-interval ratios in both groups.The application of these results to theories about the mechanisms underlying the alterations in mechanical performance induced by hypertrophy is discussed.CHANGES IN THE mechanical properties of isolated cardiac muscle accompanying pressure-induced hypertrophy have been the subject of a number of investigations, but no unanimous view has yet emerged.Bassett and Gelband, 1 Kaufmann et al., 2 and Cooper et al. 3 reported the peak force per cross-sectional area developed by papillary muscles from hypertrophied hearts to be less than that from control hearts, whereas Pannier, 4 Spann et al., 5 Grimm et al.,6 Fisher and Kavaler, 7 and Bing et al. 8 found no significant differences between the two groups; Kerr et al. 9 found the force per muscle weight to be greater in hypertrophied hearts.Similarly, Spann et al., Bassett and Gelband, and Cooper et al. found the maximum rate of force development per cross-sectional area to be depressed in hypertrophied hearts, whereas Pannier and Fisher and Kavaler found no significant difference.Jouannot and Hatt 10 and Williams and Potter" found that, after banding, peak force and maximum rate of force development declined at first and then returned to the control values.The effect of hypertrophy on the force-velocity relationship is similarly controversial.Some investigators found the force-velocity relationship to be depressed, 2 -5
Source: Circulation Research
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Award: G8074571015
OpenAlex ID: W2151403971