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The effects of atrial pacing and dynamic exercise in the supine position on systolic time intervals (STI) were compared in 10 normals. In another group of 13 normals, the effect of exercise alone on STI was tested. A linear shortening of electromechanical systole (QS2) and left ventricular ejection time (LVET) with increasing heart rate was demonstrated with right atrial pacing and dynamic exercise in the frequency range between 60 and 140 beats/min. However, the shortening of LVET was significantly less (p less than 0.01) with exercise compared to pacing. This is explained by an increase in left ventricular stroke volume with exercise. The preejection period (PEP) was significantly (p less than 0.001) shortened with exercise, but there was no change with atrial pacing. Thus, changes in heart rate (HR) alone, without changes in the dynamic state of the heart, did not influence PEP. It is suggested that PEP at rest should not be corrected for heart rate. The supine exercise regression equations for correction of heart rate for LVET and PEP differ from both the resting and the upright exercise regression equations. With exercise a frequency correction of STI using regression equations should be abandoned. Instead, uncorrected STI at standard heart rates (e.g., 100, 110, and 130 beats/min) should be taken for comparison. Heart rate standardization should be employed using the formula: Formula (See Text).

Abstract. A disseminated atrophy of the proximal tubule accompanies KzHP04-induced nephropathy in dogs. These pathologic processes cause glomerular changes that pass through different inflammatory stages and terminate in glomerular sclerosis.Experimental animals, design of the experiment and methods have been described [ 151. During the 14-week study we determined the amount of urine (24 hours), protein (mg/dl), protein excretion (mg protein/24 hr) and the macro-and microprotein fraction in the urine by SDS-polyacrylamide gel electrophoresis. Clinical examinations were at 15, 66, and 85 days.Beagle dogs treated with 0.8 g KzHP04/kg body weight developed significant glomerular selective and unselective proteinuria. During the experiment the macroproteins in the urine decreased markedly, and at the last examination (day 85) glomerular proteinuria was no longer detectable by electrophoresis.Morphologically, there were only slight glomerular changes in the biopsy material taken at four weeks. Widespread lesions at 14 and 38 weeks were dilatation of Bowman's space, thickening of the basement membrane, increase in mesangial matrix, interposition of nonargentophilic mesangial matrix into the glomerular basement membrane, protein deposits in the mesangium and parietal basement membrane, formation of crescents, shrinkage of the glomeruli with collapse of glomerular tufts, and finally glomerular sclerosis. The parietal epithelial cells contained cytoplasmic areas that were free of organelles and contained microfilamentous and fine-granular material. These areas were close to the capsular basement membrane. Bundles of filaments within parietal epithelial cells had contact with the basement membrane, thus resembling hemidesmosomes.The sequelae of tubular atrophy are retention of glomerular filtrate and dilatation of Bowman's space, followed by compression and shrinkage of the glomerular tufts, and inflammatory processes within the glomerulus. The latter may be characterized as mesangio-sclerosing, mesangio-proliferative, membrano-proliferative, and extra-capillary glomerulonephritis. The decrease of urinary protein excretion towards the end of the experiment may be related to intratubular lysosomal digestion of cellular and amorphous components.

1 A single-blind randomized study of the effects of a 3-adrenoceptor antagonist with intrinsic sympathomimetic activity (pindolol 0.4 mg i.v., n = 10) and a drug lacking this property (metoprolol 5 mg i.v., n = 11) on local wall motion abnormalities was carried out in 21 patients with coronary heart disease and anterior wall hypokinesia. 2 The drugs produced similar changes in left ventricular end diastolic pressure (LVEDP) and end diastolic volume index (EDVI) but differed in their effects on heart rate and ejection fraction. Pindolol did not exert any marked effect on heart rate or ejection fraction whereas after metoprolol treatment both were significantly decreased. 3 Shortening of the hypokinetic wall segments was improved by both drugs. Shortening of the non-hypokinetic contralateral segments was unchanged after pindolol administration but was decreased after metoprolol.4 The differing effects of f-adrenoceptor antagonists on regional wall motion appear to be dependent on the presence or absence of intrinsic sympathomimetic activity.

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