THE EFFECTS OF INTRAVENTRICULAR PERIVENTRICULAR BLOOD ON CEREBRAL 3',5'-CYCLIC ADENOSINE-MONOPHOSPHATE CONCENTRATION AND CEREBROVASCULAR REACTIVITY IN NEWBORN PIGS/

This study investigated the effects of intraventricular/periventricula r blood on cerebral cAMP production and cortical cerebrovascular react ivity. Under halothane and N2O anesthesia, 3 mL of either autologous b lood or artificial cerebrospinal fluid (CSF) were injected into the le ft caudate nucleus; Volume was adequate to result in extrusion of flui d or blood into the lateral ventricles of 1-2-d-old piglets. Twenty-fo ur hours later, a closed cranial window was implanted over the left pa rietal cortex. Pial arteriolar responses to vasodilator and vasoconstr ictor stimuli were monitored. Before the application of Vasoactive age nts, cortical periarachnoid CSF was collected for cAMP measurement. Pi al arteriolar responses to topical application of endothelin-1 (10(-9) and 10(-8) M) and to leukotriene C-4 (10(-10) and 10(-9) M) were simi lar between the two groups. However, pial arteriolar responses to topi cal application of cAMP-mediated vasodilators, prostaglandin E-2 (10(- 6) and 10(-5) M), and histamine (10(-6) and 10(-5) M), respectively, w ere markedly reduced in the blood group when compared with the artific ial CSF (control) group. Mean CSF cAMP level in the blood group was si gnificantly lower than the control group (199 +/- 31 versus 1092 +/- 2 38 fmol/mL, p = 0.0006). We conclude that in newborn pigs intraventric ular/periventricular blood results in a marked reduction of CSF cAMP c oncentration and attenuation of the cerebrovascular responses to cAMP- mediated vasodilators on the cortical surface remote from the site of blood or hematoma.