Effects of Aging on the Regulation of Intracellular pH in the Rat Jejunum

• Published in: The journals of gerontology. Series A, Biological sciences and medical sciences Vol. 51A; no. 5; pp. B346 - B353
• Main Authors: Ikuma, Mutsuhiro, Hanai, Hiroyuki, Kaneko, Eizo, Hayashi, Hisayoshi, Hoshi, Takeshi
• Format: Journal Article
• Language: English
• Published: United States The Gerontological Society of America 01-09-1996; Gerontological Society of America; Oxford University Press
• Subjects: Aging; Aging - metabolism; Amiloride - pharmacology; Ammonium Chloride - pharmacology; Animals; Cellular biology; Fluoresceins; Gerontology; Hydrogen-Ion Concentration; In Vitro Techniques; Jejunum - cytology; Jejunum - metabolism; Male; Microscopy, Fluorescence; Rats; Rats, Wistar; Rodents; Sodium - pharmacology
• ISSN: 1079-5006; 1758-535X
• DOI: 10.1093/gerona/51A.5.B346

Jejunal villus cells from young-adult (6 months) and senescent (24 months) male Wistar rats were studied to evaluate the effect of aging on intracellular pH (pHi regulation. pHi was measured by quantitative fluorescence microscopy by using BCECF-AM [2′,7′-bis(carboxyethyl)-5(6)-carboxy-fluorescein acetoxy methylester] under basal conditions and after inducing cytoplasmic acidification with pulsed NH4 Cl. In the senescent rats, the recovery rate from the acidified levels was significantly lower than that in the young-adult rats (.208 ± .005 vs .255 ± .004 pH units/min). The relationship between pHi recovery and external Na+ concentration followed Michaelis-Menten type kinetics, the maximum velocity (Vmax of alkalinization being significantly lower in the senescent rats than in the young-adult rats (.227 ± .033 vs .297 ± .024 pH units/min). These results indicate that the recovery of pHi from an acidic level was slower in the senescent rats, due to the reduced activity of Na+/H+ exchange as revealed by the decreased Vmax value.