Tan A C, Jansen T L, Thien T, Kloppenborg P W, Benraad T J
Department of Experimental and Chemical Endocrinology, St. Radboud Hospital, University of Nijmegen, The Netherlands.
J Am Geriatr Soc. 1993 Nov;41(11):1241-4. doi: 10.1111/j.1532-5415.1993.tb07309.x.
To compare the sensitivity to atrial natriuretic peptide (ANP) in young and elderly subjects.
Double-blind, random-order, placebo-controlled study using two different rates of ANP infusion.
Eight healthy young (23 +/- 3 years, mean +/- SD) and eight healthy elderly (76 +/- 4 years) subjects recruited from the general population.
Plasma cyclic guanosine monophosphate (cGMP, the second messenger of ANP) levels reflecting the sensitivity of biologically active ANP receptors.
Baseline ANP levels were higher and rose to a greater extent in the elderly both during low- (0.25 microgram/min) and high-dose (2.0 micrograms/min) infusion of ANP. Plasma levels of cGMP rose in proportion to the increase in ANP. When the rise in cGMP levels was related to the increase in ANP levels (expressed as nmol/L per 100 pg/mL ANP increase), no difference was found between young and elderly subjects.
The ability of elderly subjects to increase cGMP in response to exogenous ANP is similar to that of young subjects. This may reflect a similar sensitivity of the target organs towards ANP. However, because of lower clearance in the elderly, a similar dose of ANP results in a greater elevation of ANP and cGMP levels and hence induces a greater effect.
