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SUMMARY Regional cerebral blood flow (rCBF) was measured in normotensive rats (NTR) and spontaneously hypertensive rats (SHR), in a lightly anesthetized state and with control of Paco s by artificial ventilation. Without carotid artery ligation, NTR and SHR showed almost identical rCBF values and distribution, despite significantly elevated levels of blood pressure in SHR. Bilateral carotid artery ligation, however, caused much more pronounced decreases of rCBF (ischemia) in SHR than NTR, in regions supplied by the carotid artery. The reduction of rCBF in SHR was rather homogenous and symmetrical.Mechanisms causing the differences between NTR and SHR are discussed.CEREBRAL BLOOD FLOW (CBF) in patients with benign arterial hypertension is known to be not much different from that in normotensives.1 In animals, Strandgaard et al. 2observed no significant differences in CBF between baboons with normotension and Goldblatt hypertension.On the other hand, bilateral ligation of the common carotid arteries in spontaneously hypertensive rats (SHR) is known to cause a much greater increase in anaerobic metabolites in the brain 3 and a more severely reduced reactivity of the cortical arterioles to vasodilating agents 4 than in normotensive Wistar rats (NTR), as well as more extensive infarcts in the regions supplied by the carotid artery.6 These findings suggest that bilateral carotid ligation causes more severe ischemic damages to the brain in SHR. Actual values of cerebral blood flow, however, were not measured in these experiments.The present study was designed to compare the regional cerebral blood flow (rCBF) values in SHR with those in NTR, before and after bilateral ligation of the common carotid arteries. MethodsSixteen female NTR and 18 SHR ranging in weight from 180 to 330g and in age from seven to 12 months were used. The animals were lightly anesthetized with amobarbital (100 mg/kg) injected intraperitoneally and a tracheostomy was made. A short polyethylene catheter was placed in the aorta through the right iliac artery for sampling arterial blood and for monitoring blood pressure with a strain gauge and polygraph. Two venous catheters were passed transfemorally, one into the inferior vena cava for the injection of a diffusible radioactive indicator, antipyrine labelled with carbon-14, and the other into the right iliac vein for an arterial-venous shunt. Rectal temperature was kept between 36 and 37°C with a heat lamp. Each rat was paralyzed with a minimal dose of decamethonium (initially 10 mg/kg, injected intravenously, with 5 mg/kg added when needed) and ventilated artificially with a respirator (Rodent Respirator model 680, Harvard). The ventilating mixture consisted of room air to which small amounts of oxygen were added. Reprints requests to Dr. Choki.Paco 2 was maintained constant between 30 and 40 mmHg; Pao 2 was maintained above 100 mmHg. In 6 NTR and 10 SHR (experimental group), both common carotid arteries were doubly ligated after careful dissection and separation of the cervical vago-sympathetic tr...

Abstract• Lactate and pyruvate concentrations and acid-base balance in cerebrospinal fluid (CSF) and arterial blood were determined in patients with intracranial hemorrhages (28 subarachnoid hemorrhages and 15 intracerebral hemorrhages).A greater increase in CSF lactate and lactate-pyruvate ratio (L/P ratio) was observed in patients with impairment of consciousness, focal neurological deficits, poor prognosis, or CSF pressures higher than 300 mm H 2 O. A combination of CSF lactate greater than 2.5 mM per liter, L/P ratio above 20, bicarbonate less than 20.4 mEq per liter, pH below 7.276, or arterial PCO2 below 31.5 mm Hg seems to indicate a poor prognosis from intracranial hemorrhage.The mechanism of hyperventilation in acute cerebrovascular diseases and of CSF pH regulation in acid-base disturbances was also discussed.

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