Impaired ATP availability at adenylate cyclase site in platelets from older subjects
Jeenapongsa R., Thomas TH., Ford GA.
We determined whether altered availability of ATP for platelet adenylate cyclase is a factor in altered response to PGE1stimulation in the elderly. Saponin 20 ug/ml permeabilization was used to deliver exogenous ATP into platelets. In platelets from young subjects (n=11, 31yrs) cAMP production rate in first 2 min was faster in intact compared to permeabilized platelets (1.9±0.3 vs 0.6±0.3 pmol/106, P<0.01) but was eventually higher in permeabilized platelets. cAMP production at 15 min was similar in intact platelets from young and elderly (n=9, 72yrs) subjects (4.2±0.4 vs 5.0±0.9 pmol/106, P=0.28) but was greater in older subjects with exogenous ATP (10.0±1.2 vs 6.0±0.5 pmol/106, P=0.02). Platelet adenylate cyclase activity is limited by ATP availability which is impaired in older subjects.