Studies concerning the role of myocardial hypertrophy and of intramural tension as determinants of the increased voltage in concentric left ventricular hypertrophy.
In order to study the role of myocardial hypertrophy and of the intramural tension as determinants of the increased voltage in concentric left ventricular hypertrophy, the amplitude of intracellular action potentials in frog and rat myocardium and of monophasic action potentials recorded in dogs by suction electrodes were studied. Increased amplitudes of intracellular action potentials were seen neither in experimental LVH in rats nor during stretch in frog and rat myocardium. The increased intramural tension in dog heart during norepinephrine perfusion or in heart-lung preparation during increased peripheral resistance does not increase the amplitude of monophasic action potentials. The abrupt hypertension induced by norepinephrine is an inadequate model for the study of the effect of increased intramural tension. The increase of the voltage in LVH cannot be accounted for by the increase of action potentials of each hypertrophied fibre. Many factors cooperate in producing increased voltage of LV in LVH.
D000818:Animals; D001001:Anura; D001696:Biomechanical Phenomena; D006332:Cardiomegaly / Q000503:physiopathology*; D004285:Dogs; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology*; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009200:Myocardial Contraction; D009638:Norepinephrine; D010210:Papillary Muscles / Q000503:physiopathology; D051381:Rats
D009638:Norepinephrine