title: Loss of water from heart muscle cells during aging of rats as measured by X-ray microanalysis.
abstract: Age-dependent changes of the intracellular water content (IWC) of the rat myocardium have been measured by X-ray microanalysis of deep-frozen bulk specimens (Zs.-Nagy et al., 1982), using a slow warming up and drying of a very superficial layer of the sample, in order to minimize space charging effects. These results were compared with those calculated from the conventionally measured tissue water contents (TWC) and data from literature of morphologically estimated volume density of the extracellular space (David et al., 1981). The IWC values obtained from these two independent methods are in very good agreement, showing that the etching of the surface during the bulk specimen analysis is sufficiently small, i.e., it does not result in any considerable error in the quantitative X-ray microanalysis. The IWC of heart muscle cells decreases significantly with advancing age (from about 80% by weight at the age of 14 days to 71% by the age of 24 months). This observation is consistent with the membrane hypothesis of aging (Zs.-Nagy, 1978). Comparison of the IWC with TWC of the heart muscle shows that the increase of the volume density of the extracellular space during aging balances the age-dependent loss of myocytes to a certain extent.
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D001834:Body Water / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D005110:Extracellular Space / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains