Biomedical subjects

M Rockstein

Publications and source records attributed to M Rockstein.

18 recordsLinked to original sources

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