Hypertrophied ventricles from spontaneously hypertensive rats demonstrate altered diastolic properties and increased excitability compared to normotensive controls.
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Altered diastolic properties and excitability in SHR ventricles may inform arrhythmia mechanisms; leaves open clinical relevance pending human studies.
Isovolumetric pressure-producing properties of isolated Langendorf-perfused hypertrophied ventricles from adult spontaneously hypertensive rats (SHR) were compared with those of nonhypertrophied ventricles from adult Wistar-Kyoto rats (WKY). SHR ventricles were found to produce greater systolic pressure than WKY ventricles when subjected to similar stimulation and perfusion conditions. Correction for the differences in ventricular mass eliminated the difference between groups. Apparent diastolic pressure at high stimulus rates was higher in SHR than WKY, and SHR developed exaggerated aftercontractions following cessation of high-frequency stimulation. Refractory periods of hypertrophied ventricles determined by paired-pulse stimulation were not found to be different from nonhypertrophied ventricles, but hyperexcitable periods of SHR ventricles were significantly longer than WKY ventricles. In addition, the intrinsic ventricular rate of SHR preparations was significantly greater than that of WKY.
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Lois Jane Heller (1981) studied this question.
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