Wagerle L C, Kumar S P, Belik J, Delivoria-Papadopoulos M
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia 19104.
J Appl Physiol (1985). 1988 Aug;65(2):776-81. doi: 10.1152/jappl.1988.65.2.776.
The present study investigates the integrity of the blood-brain barrier to H+ or HCO3- during acute plasma acidosis in 35 newborn piglets anesthetized with pentobarbital sodium. Cerebrospinal fluid acid-base balance, cerebral blood flow (CBF), and cerebral oxygenation were measured after infusion of HCl (0.6 N, 0.191-0.388 ml/min) for a period of 1 h at a constant arterial PCO2 of 35-40 Torr. HCl infusion resulted in decreased arterial pH from 7.38 +/- 0.01 to 7.00 +/- 0.02 (P less than 0.01). CBF measured by the tracer microsphere technique was decreased by 12% from 69 +/- 6 to 61 +/- 4 ml.min-1.100 g-1 (P less than 0.05). Infusion of 0.6 N NaCl as a hypertonic control had no effect on CBF. Cerebral metabolic rate for O2 and O2 extraction was not significantly changed from control (3.83 +/- 0.20 ml.min-1.100 g-1 and 5.7 +/- 0.6 ml/100 ml, respectively) during acid infusion. Cerebral venous PO2 was increased from 41.6 +/- 2.1 to 53.8 +/- 4.0 Torr by HCl infusion (P less than 0.02) associated with a shift in O2-hemoglobin affinity of blood in vivo from 38 +/- 2 to 50 +/- 1 Torr. Cisternal cerebrospinal fluid pH decreased from 7.336 +/- 0.014 to 7.226 +/- 0.027 (P less than 0.005), but cerebrospinal fluid HCO3- concentration was not changed from control (25.4 +/- 1.0 meq/l). These data suggest that there is a functional blood-brain barrier in newborn piglets, that is relatively impermeable to HCO3- or H+ and maintains cerebral perivascular pH constant in the face of acute severe arterial acidosis. (ABSTRACT TRUNCATED AT 250 WORDS)
本研究调查了35只戊巴比妥钠麻醉的新生仔猪在急性血浆酸中毒期间血脑屏障对H⁺或HCO₃⁻的完整性。在动脉PCO₂恒定为35 - 40 Torr的情况下，输注HCl（0.6 N，0.191 - 0.388 ml/min）1小时后，测量脑脊液酸碱平衡、脑血流量（CBF）和脑氧合情况。输注HCl导致动脉pH从7.38±0.01降至7.00±0.02（P<0.01）。用示踪微球技术测量的CBF从69±6降至61±4 ml·min⁻¹·100 g⁻¹，降低了12%（P<0.05）。输注0.6 N NaCl作为高渗对照对CBF无影响。在酸输注期间，脑氧代谢率和氧摄取率与对照相比无显著变化（分别为3.83±0.20 ml·min⁻¹·100 g⁻¹和5.7±0.6 ml/100 ml）。HCl输注使脑静脉PO₂从41.6±2.1升至53.8±4.0 Torr（P<0.02），同时体内血液中氧合血红蛋白亲和力从38±2 Torr变为50±1 Torr。枕大池脑脊液pH从7.336±0.014降至7.226±0.027（P<0.005），但脑脊液HCO₃⁻浓度与对照相比无变化（25.4±1.0 meq/l）。这些数据表明，新生仔猪存在功能性血脑屏障，其对HCO₃⁻或H⁺相对不通透，并且在急性严重动脉酸中毒时能维持脑周血管pH恒定。（摘要截选至250字）
