title: Age-related difference in the in vitro response of erythropoietin to triiodothyronine in male rats.
abstract: The effect of aging on medium erythropoietin (EPO) levels after triiodothyronine (T3, 1 nM) stimulation in vitro and on the EPO content of kidney extract were investigated. Middle (mid)-aged (17 months), adult (6 months) and young (3 months) male rats were decapitated. The kidneys were decapsulated and cut into 6 equal pieces. One sixth of the kidney was extracted by phosphate buffer before measuring the content of EPO in kidney and one sixth of the kidney was incubated in vitro with T3 (1 nM) at 37 degrees C for 30 min. The concentration of EPO in both medium and kidney extract was measured by a radioimmunoassay (RIA). The EPO content in kidney was higher (p < 0.05) in the mid-aged than in the young rats. The basal level of medium EPO was not changed by age. Only young rather than adult or mid-aged rats showed an increase of EPO secretion after T3 stimulation (p < 0.01). These data suggest that the EPO concentration in rat kidney and the action of T3 on EPO release from the kidney are age-dependent.
authors.affiliation: Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
authors.forename: R Y
authors.initials: RY
authors.lastname: Wang
authors.forename: S C
authors.initials: SC
authors.lastname: Tsai
authors.forename: P S
authors.initials: PS
authors.lastname: Wang
mesh_terms: D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000818:Animals; D004921:Erythropoietin / Q000032:analysis / Q000378:metabolism*; D066298:In Vitro Techniques; D007668:Kidney / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D014284:Triiodothyronine / Q000494:pharmacology*
chemical_list: D014284:Triiodothyronine; D004921:Erythropoietin