Influence of age on venodilator effect of isoproterenol and amrinone.
OBJECTIVE
To investigate the influence of age on the venodilator effect of isoproterenol, a beta-adrenoceptor agonist, and amrinone, a selective phosphodiesterase (PDE) III inhibitor, in human subjects.


METHODS
In eight young and eight elderly male subjects, the drugs were infused into a dorsal hand vein preconstricted with phenylephrine and its diameter was measured using a linear variable differential transformer.


RESULTS
The maximum venodilation (Emax) induced by isoproterenol was significantly smaller and the infusion rate of isoproterenol required to induce 50% of maximum venodilation (ED50) was significantly larger in the elderly than in the young subjects [Emax: 29.8 vs 95.1%, ED50: 97.3 vs 51.6 ng.min-1]. A significant age-related change in Emax or ED50 was not observed for amrinone (Emax: 95.8 vs 100.8%, ED50: 40.1 vs 31.6 micrograms.min-1).


CONCLUSIONS
The data show that the venodilator effect of amrinone is not influenced by age. As amrinone increases cyclic AMP by inhibition of PDE III, it is suggested that the action of cyclic AMP is not altered by age. The decreased effect of isoproterenol might be caused by reduced production of cyclic AMP in elderly subjects.
Harada
K
K
Department of Clinical Pharmacology, Jichi Medical School, Tochigi, Japan.
Ohashi
K
K
Kumagai
Y
Y
Ohmori
M
M
Fujimura
A
A
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000676:Amrinone / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D006225:Hand / Q000098:blood supply; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D011674:Pulse / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*; D014680:Veins / Q000187:drug effects*
D000318:Adrenergic beta-Agonists; D014665:Vasodilator Agents; D000676:Amrinone; D007545:Isoproterenol