Effect of Intravenous Dipyridamole on Cerebral Blood Flow in Humans

Abstract

Background and Purpose-Dipyridamole increases the concentration of circulating adenosine, which is a potent vasodilator, by inhibition of uptake of adenosine into the erythrocytes, and hence produces coronary vasodilation. However, the effects of dipyridamole on cerebral circulation is not pronounced. This study investigates the effects of intravenous dipyridamole on cerebral blood flow (CBF) in humans with use of positron emission tomography (PET). Methods-In each of 13 healthy subjects, CBF was measured using 15 O-labeled water and PET at rest and during hypercapnia, hypocapnia, and dipyridamole stress; corresponding CBF values were then compared. Results-CBF values during dipyridamole stress were significantly lower than those measured at rest. The dipyridamole stress PaCO 2 was also significantly lower than the resting PaCO 2 . The change in CBF during dipyridamole stress relative to PaCO 2 closely followed the relationship between CBF and PaCO 2 during hypocapnia. Conclusions-These results indicate that the observed decrease in CBF during dipyridamole stress was caused by a decrease in PaCO 2 rather than by any direct action of dipyridamole on CBF. The decrease in PaCO 2 during dipyridamole stress was most likely due to hyperventilation, which was a side effect of adenosine. These results support the hypothesis that circulating adenosine is largely prevented from binding to adenosine receptors of cerebral vessels by the blood-brain barrier. (Stroke. 1999;30:1616-1620.)

Heart and brain circulation and CO2 in healthy men

“…Thirteen healthy men (age range 51–71 years; mean 59.4, standard deviation 5.5) who had been the subjects of previously published studies with different objectives (Iida et al. 1998, Ito et al. 1999, 2000, 2002) took part in the study.…”

Multifunctional Actions of Approved and Candidate Stroke Drugs

“…29 The effect of dipyridamole on cerebral blood flow is, however, not fully understood. 30,31 Dipyridamole possesses antithrombotic properties in the vessel wall by enhancing the production of the endogenous platelet inhibitor prostacyclin, thereby preventing platelet adhesion to the endothelium. 32,33 Damage caused by hydrophilic and hydrophobic radicals can be prevented by the scavenger properties of dipyridamole.…”

Pseudocontinuous Arterial Spin Labeling Reveals Dissociable Effects of Morphine and Alcohol on Regional Cerebral Blood Flow

“…Global change in cerebral blood flow (CBF) is an important marker of cerebral autoregulation (Heiss and Podreka, 1978), whereas the regional distribution of CBF might reflect drug effects on functional brain activity. Initially, 15 O-PET was used to detect drug effects on cerebral circulation (Ito et al , 1999; Volkow et al , 1988). However, replication and repetition of positron emission tomography (PET) studies is costly and not widely available.…”