ENDOTHELIN (ET-1). ENDOTHELIN 3 (ET-3) AND BIG ENDOTHELIN (BigET) LEVELS IN CSF AND ARTERIAL BLOOD DURING HYPER AND HYPOCAPNIA IN PIGLETS

摘要

To determine possible vascular mediators that might explain cerebrovascular paralysie associated with perinatal asphyxia, the levels of ET-1, ET-3 and BigET were studied in 6 lightly anesthetized ventilated 1-5 days old piglets at different PaCO2 levels in normoxia; normocapnia (NCO2. baseline BL1), hypercapnia, normocapnia (BL2), hypocapnia. At the same lime, cerebral blood flow (CBF) was measured using radiolabeled microspheres. At BL1, ET-1 level was very low in the CSF and remained stable throughout the study. In arterial blood, ET-1 was low or undetectable. Et-3 was delected only during hypercapnia only (31.9 ± 49 pg/ml) in CSF and remained stable in arterial blood. BigET levels were similar throughout the study and not affected by PaCO2 either in CSF and arterial blood. CBF rose dramatically as expected during hypercapnia.These data show that hypercapnia or hypocapnia are not associated to any significant changes in ET-1 levels in CSF. The detection of ET-3 during hypercapnia might, however, suggest a production of ET-3. The role of ET-1 in the CO2 cerebrovascular reactivity remains to be determined.