SUMMARYThe goal was to describe the metabolic profile of ganglionic and cortical arteries and arterioles in aging normotensive male rats. Five enzymes indicative of key metabolic pathways in the vessel walls were semiquantitatively evaluated using bright-field histochemical microscopy. Lactate dehydrogenase showed significant reactivity which increased with vessel diameter in cortical and ganglionic vessels in all age groups tested. Succinate dehydrogenase and cytochrome oxidase showed little reactivity in both cortical and ganglionic vessels, suggesting a reduced role for aerobic metabolic pathways. Myosin ATPase reactivity was high in cortical and ganglionic vessels. Only this enzyme showed an increased reactivity that was correlated with the age and diameter of the vessel. Glucose-6-phosphate dehydrogenase reactivity was more pronounced in cortical than ganglionic vessels, suggesting that the hexose-monophosphate-shunt may be more active in the cortical vessels. There were no regional differences in enzyme reactivity throughout the caudatoputamen. In conclusion, both the cortical and ganglionic vessels are metabollcally active, with significant anaerobic gh/colysis, and reduced, but observable capacity for aerobic metabolism. The decreased myosin ATPase reactivity and the low level of glucose-6-phosphate dehydrogenase reactivity in the ganglionic arterioles of senescent rats may contribute to the susceptibility of these vessels to cerebrovascular accidents. Stroke Vo! 16, No 2. 1985 THE ARTERIAL SUPPLY to the cerebrum and subcortical structures in the rat and man have many similarities, particularly in the pathophysiology of stroke. Terminal branches of the internal carotid arteries, branches from the anastomotic circle, and the posterior cerebral arteries supply the cerebral cortex in rat and man.2 3 All of these vessels provide a dense network of ganglionic arterioles that nourish the basal ganglia, including the caudatoputamen (CPU) and globus pallidus.3 Although the vascular bed of the cerebrum and subcortical structures have been described, little is yet known regarding the metabolism of these vessels.4 " 8 Furthermore, even though age-related structural changes are reported for both cortical and ganglionic vessels in man and other experimental animals, 9 "' 5 virtually nothing is known regarding the effects of aging on cerebral vascular metabolism.The present study utilizes histochemical methodology to semiquantitatively evaluate enzymes of key metabolic pathways in the muscular walls of vessels supplying the neocortex (cortical vessels) and ganglionic vessels in the CPU of aging normotensive male rats. The five enzymes evaluated are indicators of anaerobic glycolysis, the Krebs cycle and respiratory chain (aerobic metabolism), the hexose-monophosphate-shunt, and the availability of myosin ATPase. Our goal was to delineate the metabolic profile of aging stroke-prone ganglionic vessels and of cortical vessels, from which the former arise. Methods Twenty-three male rats (Charles River, COBS CD outbred ...