Jeffrey A. Chesky

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.

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.

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.

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.

The intrinsic nature of the loss of actomyosin ATPase activity during senescence in the male house fly, Musca domestica L.

Abstract Neither changing the conditions of diet under which adult male house flies are maintained, nor the complete elimination of flight by surgically removing the wings at emergence, affects the age-related loss of actomyosin ATPase activity. These studies strongly support the intrinsic nature of the biochemical senescence of thoracic flight muscle in this species.

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.

Properties of natural actomyosin from the male housefly, Musca domestica

Abstract The kinetic properties of natural actomyosin (myosin B) ATPase, isolated from adult male houseflies, were examined. The ATPase was inhibited by increasing concentrations of KCl. At low ionic strength, both substrate inhibition and product inhibition were observed. The optimal temperature for ATPase activity was 45°C. Magnesium ions were necessary to activate the ATPase, and the enzyme was inhibited by 2 m M EGTA. Therefore, it was concluded that housefly actomyosin ATPase is quite similar to that of other species. The principal unique property of the housefly preparation (as in other insects with asynchronous flight muscles) is that the ATPase is activated by lower concentrations of calcium than the actomyosin ATPase of other species.

Actomyosin ATP-sensitivity in the aging male house fly, Musca domestica L.

Abstract Natural actomyosin was extracted from the thoracic flight muscle of newly emerged, mature, middle-aged, and senescent male house flies. The age-related change in the ATP-sensitivity of the actomyosin parallels the age-related distribution of the specific activity of the actomyosin ATPase, being significantly lower in the actomyosin of newly emerged and senescent male house flies than in the actomyosin extracted from mature organisms. These results indicate that the isolated flight muscle protein is, indeed, different for various ages of the house fly, most likely consisting of different ratios of the individual components of actomyosin.

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.