Showing papers by "Edward G. Lakatta published in 1984"

Normal Human Aging: The Baltimore Longitudinal Study on Aging

Abstract: Normal Human Aging is an overview of the first 23 years of research findings about the natural course of human aging. The Baltimore Longitudinal Study of Aging was started in 1958 to "trace the effects of aging in humans." The BLSA recruited men aged 17 to 96 and women beginning in 1978 to participate in repeated assessments of health and physical and psychological performance. Visits were every two years over 2 1/2 days.

Exercise cardiac output is maintained with advancing age in healthy human subjects: cardiac dilatation and increased stroke volume compensate for a diminished heart rate.

Abstract: To assess the effect of age on cardiac volumes and function in the absence of overt or occult coronary disease, we performed serial gated blood pool scans at rest and during progressive upright bicycle exercise to exhaustion in 61 participants in the Baltimore Longitudinal Study of Aging. The subjects ranged in age from 25 to 79 years and were free of cardiac disease according to their histories and results of physical, resting and stress electrocardiographic, and stress thallium scintigraphic examinations. Absolute left ventricular volumes were obtained at each workload. There were no age-related changes in cardiac output, end-diastolic or end-systolic volumes, or ejection fraction at rest. During vigorous exercise (125 W), cardiac output was not related to age (cardiac output [1/min] = 16.02 + 0.03 [age]; r = .12, p = .46). However, there was an age-related increase in end-diastolic volume (end-diastolic volume [ml] = 86.30 + 1.48 [age]; r = .47, p = .003) and stroke volume (stroke volume [ml] = 85.52 + 0.80 [age]; r = .37, p = .02), and an age-related decrease in heart rate (heart rate [beats/min] = 184.66 - 0.70 [age]; r = -.50, p = .002). The dependence of the age-related increase in stroke volume on diastolic filling was emphasized by the fact that at this high workload end-systolic volume was higher (end-systolic volume [ml] = 3.09 + 0.65 [age]; r = .45, p = .003) and ejection fraction lower (ejection fraction = 88.48 - 0.18 [age]; r = -.33, p = .04) with increasing age. These findings indicate that although aging does not limit cardiac output per se in healthy community-dwelling subjects, the hemodynamic profile accompanying exercise is altered by age and can be explained by an age-related diminution in the cardiovascular response to beta-adrenergic stimulation.

Excitation-contraction in rat myocardium: alterations with adult aging

Abstract: Simultaneous transmembrane action potential (TAP) and isometric contraction measurements were made in thin right ventricular papillary muscles isolated from senescent (S, 24-26 mo) and young adult ...

Calcium-dependent mechanical oscillations occur spontaneously in unstimulated mammalian cardiac tissues.

Abstract: In quiescent rat ventricular myocardium, bathed in solution of 2 mM Ca++ or less, it has been previously demonstrated that spontaneous microscopic oscillatory cell motion is present and interacts with an incident laser beam to produce scattered light intensity fluctuations which can be monitored to quantify the underlying motion. The present study shows that scattered light intensity fluctuations are not present under any conditions in frog atrial or ventricular preparations, but do occur in each type of mammalian cardiac tissue studied in the unstimulated state. The magnitude of scattered light intensity fluctuations in mammalian tissues varies with species and cellular Ca++ loading. In some tissues, e.g., rabbit or ferret ventricle, either an increase in the Ca++ concentration in the perfusate [( Ca++]e), reduction of perfusate Na+ concentration [( Na+]e), or addition of cardiac glycosides was required to elicit scattered light intensity fluctuations; in other tissues, however, e.g., the canine Purkinje fiber, atria, and ventricle, and guinea pig atria, scattered light intensity fluctuations were present at 2 mM [Ca++]e in the absence of experimental Ca++ loading. Scattered light intensity fluctuations were not affected by LaCl3, or verapamil, and were reversibly abolished by caffeine. When the pCa in the myofilament space is kept constant in detergent "skinned" fibers, scattered light intensity fluctuations are not present during contractile activation. We conclude: that scattered light intensity fluctuations are due to spontaneous intracellular Ca++ oscillations that require a functional sarcoplasmic reticulum; that the potential to exhibit these oscillations is a fundamental property of mammalian excitable cardiac cells; and that, in many mammalian tissues, these oscillations are present in the unstimulated state, even in the absence of experimental perturbations to enhance cell Ca++ loading.

Prevalence and prognosis of exercise-induced nonsustained ventricular tachycardia in apparently healthy volunteers.

Abstract: Although exercise-induced ventricular tachycardia (VT), whether sustained or nonsustained, is usually associated with significant organic heart disease, its prevalence, associated characteristics and prognostic significance in an asymptomatic, unreferred community-dwelling population are unknown. Therefore, the prevalence of VT associated with maximal treadmill exercise was assessed in 597 male and 325 female volunteers, aged 21 to 96 years (mean ± standard deviation 54 ± 16), from the Baltimore Longitudinal Study on Aging who were without apparent heart disease. Ten subjects, 7 men and 3 women, with exercise-induced VT were identified, representing 1.1% of those tested; only 1 was younger than 65 years. All episodes of VT were asymptomatic and nonsustained. In 9 of 10 subjects, VT developed at or near peak exercise. The longest run of VT was 6 beats; multiple runs of VT were present in 4 subjects. Two subjects had exercise-induced ST-segment depression, but subsequent exercise thallium scintigraphic results were negative in each. Compared with a group of age- and sex-matched control subjects, those with asymptomatic, nonsustained VT displayed no difference in exercise duration, maximal heart rate, or the prevalence of coronary risk factors or exercise-induced ischemia as measured by electro-cardiography and thallium scintigraphy. Over a mean follow-up period of 2 years, no subject has developed symptoms of heart disease or experienced syncope or sudden death. Thus, exercise-induced VT in apparently healthy subjects occurs almost exclusively in the elderly, is limited to short, asymptomatic runs of 3 to 6 beats usually near peak exercise, and does not portend increased cardiovascular morbidity or mortality rates over a 2-year period of observation.

Cell size and capillary supply of the hypertensive rat heart: quantitative study.

Abstract: Cardiac mass, cell size and capillary supply were studied in the hearts of spontaneously hypertensive rats (SHR) and compared to genetically similar non-hypertensive Wistar-Kyoto (WKY) of three adult ages: 5, 15 and 23 months. The left ventricular weight of SHR was not significantly greater than that of WKY at 5 months, but was 15 months and became even more so by 23 months. This increase could be attributed to hypertrophy of the individual cardiac muscle cells and therefore, the estimated total number of myocytes per left ventricle was essentially the same in all experimental groups. Various indices of the myocardial capillary supply were also investigated. Cardiac hypertrophy in older hypertensive rats was characterized by greater and more variable intercapillary spacing, which may have importance in myocardial oxygen supply.

Pathophysiology of the Aging Heart and Circulation

Abstract: Although both the prevalence and incidence of cardiovascular disease increase dramatically with advancing age, aging and disease are not synonymous Therefore, when studying the aging process in man, one must omit those changes in the elderly groups that, in reality, are due to the presence or development of disease This chapter will attempt to delineate those changes in the heart and peripheral vasculature at rest and during exercise that are thought to represent “normal” aging While these changes in and of themselves, usually cause no disability, they do provide an altered substrate on which the specific cardiovascular diseases to be discussed in subsequent chapters are superimposed The signs, symptoms, and clinical course of these pathologic processes may be modified significantly by the physiological aging of the cardiovascular system

Age-Related Alterations in β-Adrenergic Modulation of Cardiac Cell Function

Abstract: The cardiovascular system’s raison d’etre is to transport oxygen, nutrients, blood cells, and other substances to body tissues, to remove the waste products of metabolism, and to maintain constant temperature. Since these are not fixed but can vary over at least a tenfold range (i.e., from sleep to maximum exercise) the cardiovascular system, to maintain optimal efficiency, adjusts its level of function to meet the body requirements.

Effect of sodium on calcium-dependent force in unstimulated rat cardiac muscle

Abstract: It has previously been demonstrated that 1) changes in superfusate calcium concentration [Ca2+]o within the low millimolar range result in changes in "resting" force and in the light-scattering pro...

Digitalis in Congestive Heart Failure

Abstract: Excerpt To the editors: We read the interesting review by Mulrow and associates (1) and wish to clarify a few points, particularly with regard to our own study (2). Although we did not explicitly s...