Arthur H. Norris

Aging and ethanol metabolism

The effect of aging on the distribution and elimination of ethanol was studied in a group of 50 healthy subjects ranging in age from 21 to 81 yr (mean, 53.3). Ethanol was administered in a continuous 1‐hr infusion at a mean rate of 375 mg/m2 body surface area/min (equivalent to a mean dose of 0.57 gm/kg body weight). Serial blood samples for the determination of ethanol concentration were obtained at 15‐ to 30‐min intervals for up to 4 hr post irifusion. Ethanol elimination and distribution were evaluated with the aid of a two‐compartment model. Rates of ethanol elimination were not affected by age. Peak ethanol concentration in blood water at the end of the infusion period was correlated with age (r = 0.55, p ‐ 0.001). Lean body mass and total volume of distribution of the ethanol were negatively correlated with age. The smaller volume of distribution, in association with the decreased lean body mass, most likely explains the higher peak ethanol concentration found in the blood after administration of an ethanol dose on the basis of surface area in the old as compared with the young subjects. This study demonstrates that age‐related changes in body composition are important factors in the study of ethanol metabolism and its pharmacologic effects.

Age-Adjusted Standards for Creatinine Clearance

Excerpt Glomerular filtration rate (GFR) has been shown to decline with age after maturity (1). Creatinine clearance finds frequent use as a clinical estimate of GFR, and published criteria for sev...

TRENDS IN SELECTED INDICES OF BODY COMPOSITION IN MEN BETWEEN THE AGES 30 AND 80 YEARS.

In order to understand many of the biologic phenomena of aging it is necessary to know how much of the age changes which are observed in the functional capacities of the total human can be explained on the basis of a simple loss of tissue or protoplasm and how much must be ascribed to a reduced function in the protoplasm remaining (N. W. Shock, 1956). Measurement of body composition constitutes an important approach to this problem.

Age Changes in Heart Rate and Blood Pressure Responses to Tilting and Standardized Exercise

Tilting and standardized exercise caused extensive shifts of heart rate and auscultatory blood pressures in 140 ambulatory male subjects from 20 to 92 years of age. Following similar exercise, the older subjects showed a greater increase of heart rate and pulse pressure than did the younger subjects who compensated the changes caused by tilting more completely and rapidly than did the older subjects. These slower compensatory responses of older subjects should be considered in the interpretation of metabolic recovery rates after exercise.

Age-related differences in lactate distribution kinetics following maximal exercise.

SummaryLactate concentrations were determined at 3, 5, and 7 min of recovery following maximal, continuous, multi-stage treadmill work in 180 men, aged 20–80 years, who were participants of the Baltimore Longitudinal Study of Aging. Each subject was placed into one of six age groups, e.g., 20–29, 30–39, etc. As expected, average concentrations decreased consistently with age. All three sampling times were similar in characterizing maximal lactates for the youngest men. For each older group, except for the oldest, the later values were significantly (p<0.01) higher than the 3-min values. For subjects in their 50s and 60s mean concentrations continued to rise through the 7th min. These data suggest that in man there is a progressive, age-related diminution of ability to diffuse lactate from muscle and/or distribute it into its space. This may result in decreased endurance and work capacity and a prolongation of recovery. As an alternative to multiple sampling and analyses for maximal lactate, single blood samples should be obtained no sooner than 5 min of recovery for men up to age 50, and at 7 min for those between 50 and 70 years. Variability among the men over 70 years of age was large enough to preclude single-sample alternatives.