Biomedical subjects

M Rockstein

Publications and source records attributed to M Rockstein.

At least 19 recordsLinked to original sources

PubMed1981

Effects of exercise on the biochemical aging of mammalian myocardium. II. Creatine phosphokinase.

Male Fischer 344 rats from a long inbred colony (by brother-sister mating) were subjected to moderate (forced swimming) physical activity on a regular basis, beginning at 3 weeks following weaning. Normally caged, sedentary littermates were employed as controls at each age level. Exercised animals showed a greater total ventricular mass and correspondingly lower body weight, and the heart to body weight ratio for experimental animals about 25% higher at all ages, beginning at 3 months following onset of exercise. Finally, the specific activity of myocardial creatine phosphokinase was consistently higher for the exercised animals, beginning at 3 months of age and through 16 months of such exercise. These data support previous findings from this laboratory, as well as by others, that long-term moderate exercise begun early in life has a continuing, beneficial effect on the mammalian heart, both at the gross functional and intracellular biochemical levels.

Aging↗

PubMed1981

Effects of exercise on the biochemical aging of mammalian myocardium. I. Actomyosin ATPase.

Male Fischer 344 rats were subjected to regular forced exercise beginning at weaning and continued until sacrificed at ages ranging from 2 to 18 months. Littermates served as sedentary controls. At all ages examined, the exercised animals had greater heart and lower body weights. Actomyosin was isolated from the myocardium and the ATPase activity of the contractile protein preparation was measured. Only the sedentary animals exhibited an age-related loss in enzyme activity. The physically trained animals had substantially higher ATPase specific activity than the controls at all ages. This difference in ATPase specific activity may be the result of the synthesis of different isozymic forms of myosin or changes in the regulatory proteins of actomyosin (tropomyosin and troponin). It is suggested that lifelong regular exercise may alter the known biochemical changes in the heart muscle that relate to declining cardiac function.

Actomyosin↗

PubMed1981

Effect of population density upon life expectancy and wing retention in the common house fly, Musca domestica L.

In adult caged house flies, maintained on a complete diet of powdered whole milk, cane sugar and water, the median longevity, maximal longevity, and percentage that exhibit complete wing retention at death are increased as the number of individuals per cage is correspondingly decreased from 240 to 10 flies per cage. These effects are more marked for the shorter-lived males than for the females. Female longevities at all population densities are more significantly reduced by a restricted diet of sugar and water only. Under conditions of individual confinement, the life expectancy of the female house fly is no greater than that of the male. These results are in agreement with earlier suggestions that increased physical activity including interaction among individuals in a restricted population decreases longevity.

Animals↗

PubMed1981

Age-related activity changes in actomyosin ATPase and arginine phosphokinase in male Drosophila melanogaster Meig.

The specific activity of each of the two enzymes primarily concerned with the energy metabolism of flight muscle contraction was determined in male Drosophila melanogaster, from emergence through 5 weeks postemergence. Ca++-activated actomyosin ATPase activity rose rapidly from a minimum at emergence to a peak level at 4-5 days, falling gradually thereafter to a minimum level at 10-11 days postemergence, with no change thereafter. Arginine phosphokinase activity rose more gradually to a maximum at 11-12 days postemergence and then fell slowly to a minimum at 18-19 days. These data represent a sequential pattern of biochemical changes similar to those previously observed in other dipteran species, confirming the primary role of a genetic program for maturation and senescence of flight ability in holometabolous adult insects at the functional and underlying cellular, biochemical levels.

Actomyosin↗

PubMed1980

Changes with age of myocardial creatine phosphokinase in the male Fischer rat.

Myocardial creatine phosphokinase (CPK) was extracted from crushed tissue in 0.01 M Tris buffer at pH 9.0 and purified by successive ammonium chloride and ethanol precipitations. The CPK activity was estimated by measuring the rate of phosphocreatine formation by the transphosphorylation of creatine by ATP. There was a slight rise in CPK activity from 1 to 2 months of age. Thereafter, there was a progressive fall in the CPK activity of 14% by 7-9 months of age, 20% by about one year of age, and 25% by 16-24 months of age. These data indicate that, with advancing age, there is an inability to rapidly restore adequate cellular levels of the high-energy substrate ATP during muscular contraction. Since the loss with age of myocardial CPK parallels a strong biochemical correlate for known declining cardiac function in aging mammals, including man.

Actomyosin↗

PubMed1978

Calcium sensitivity of myocardial actomyosin ATPase in young and mature male Fischer rats. A brief note.

Although myocardial actomyosin ATPase specific activity determined at Ca2+ levels of 1 x 10(-3) to 1 x 10(-2) M is consistently higher in two-month old male Fischer rats than in twelve-month old individuals, this difference can be eliminated if the enzyme is assayed at lower calcium concentrations. This suggests that the previously reported, declining actomyosin ATPase activity in the rat myocardium with advancing age may represent an age-related diminished ability of calcium to reverse the known inhibition upon actomyosin ATPase by the regulatory proteins.

Actomyosin↗

PubMed1977

Reduced myocardial actomyosin adenosine triphosphatase activity in the ageing male Fischer rat.

Actomyosin was extracted from myocardial homogenates from male rats of different ages of a long-inbred Fischer rat colony maintained under controlled conditions of temperature, humidity, and light. ATPase specific activity rose to a maximum at 2 months of age; this was followed by a progressive decline by about 25% at 16 months of age. However, the extractable actomyosin remained constant during this period. This loss in actomyosin ATPase specific activity is in good agreement with previously reported decrements in both stroke index and myocardial calcium content and an increase in myocardial contraction duration in aged rats.

Actomyosin↗

PubMed1976

Life span characteristics in the male Fischer rat.

Survival data are reported for 572 male non-breeding Fischer rats, representing offspring from brother-sister matings, maintained at a constant temperature and humidity, exposed to twelve hours of artificial lighting and to twelve hours of darkness per day, and fed a standard laboratory diet ad libitum. The mean longevity for these male rats was 642 days and the median longevity was 659 days; the longest-lived individual survived to 1192 days. Animals surviving beyond the median life span for this colony were found to lose a greater percentage of body weight during the last few weeks before death than did shorter-lived animals. Offspring born of parents one year of age showed no significant difference in longevity from those of three-month old parents. Moreover, the longer any animal lived, the greater the maximan weight which he obtained.

Animals↗

PubMed1976

Fructose-1,6-bisphosphatase from young and adult rats.

Fructose-1,6-bisphosphatase (E.C. 3.1.3.11) was purified from the livers of young (69-86 days) and adult (370-386 days) Fisher rats. The enzyme preparations were examined for increasing amounts of missynthesized proteins by means of heat-inactivation as well as for differences in regulatory properties. No significant difference with respect to the fraction of rapidly heat-inactivated enzyme or Km- and Ki-values was found. These results do not support the hypothesis that error accumulation resulting in an error catastrophe is a general phenomenon underlying senescence and death.

Aging↗

PubMed1975

An electron microscopic investigation of age-dependent changes in the flight muscle of Musca domestica L.

The thoracic flight muscle from adult male NAIDM house flies was examined, from emergence to very old age. Thin sections stained with uranyl acetate and bismuth showed no myofibrillar or mitochondrial degeneration from 1 day to 19 days post-emergence, contrary to earlier reports. Some progressive loss in glycogen content and increase in mitochondrial size were observed for muscle from young to very old flies. However, there was no conclusive evidence of fusion of smaller mitochondria into larger ones with advancing age, despite exhaustive examination of representative sections of muscle samples of adult males of different ages.

Aging↗

PubMed1973