1. Extra- and intracellular potentials were recorded from neurons and glia during spreading depression (SD) in cerebral cortex of cats. The glial membrane depolarized during SD and the time course of depolarization was concurrent with the surface DC change of SD. The glial depolarization evoked by 20-Hz repetitive cortical stimulation disappeared during the negative DC shift of SD. Simultaneous recording of the extra- and intracellular potentials from a single glial cell with a coaxial microelectrode showed that the extracellular DC potential change was of opposite polarity to the glial intracellular potential, which suggests that the slow glial depolarization concurrent with SD is not the field potential. In contrast to glial cells, the neuronal burst discharges as well as the neuronal membrane depolarization associated with SD did not show a close relationship to SD: the neuronal membrane depolarization and discharge were frequently delayed by 10-3- s from the onset of the SD slow wave. Sometimes SD was observed without accompanying neuronal depolarization. The degree of neuronal depolarization was not always correlated with the amplitude of the negative wave of SD. 2. The effect of tetrodotoxin (TTX) on the negative DC potential of SD was examined. Simultaneous recording of glial membrane potential and the neuronal unit activity as well as extracellular DC potential and surface DC potential during SD was performed and the TTX-treated cortex was compared with the normal state. TTX did not change the DC level of the cerebral cortex. SD could be evoked by KCl when neuronal discharge was completely abolished by TTX application...

No abstract

No abstract

No abstract

SUMMARY Brain metabolites and arterial acid-base measurements were made one hr after bilateral carotid artery occlusion in 2 different models of hypertensive rats. Animals used included renovascular hypertensive rats (RHR) with an altered renin-angiotensin system and desoxycorticosterone hypertensive rats (DHR) with low plasma renin activity (PRA). The mean value for supratentorial lactate of 7.41 mM/kg in RHR was significantly higher than in DHR (3.90 mM/kg) or in control normotensive rats (3.10 -2.56 mM/kg). Concomitantly, the lactate/pyruvate ratio tended to increase and ATP to decrease in RHR only. In these same rats (RHR) infratentorial lactate was also increased.The results suggest that bilateral carotid occlusion leads to anaerobic metabolism of the brain in RHR but not in DHR, suggesting that the renin-angiotensin system may play some role in the susceptibility to cerebral ischemia following carotid occlusion in the hypertensive rats.Stroke Vol 10, No 5, 1979OUR PREVIOUS studies 1 ' 2 -3 have shown a great increase in cerebral lactate and in the lactate/pyruvate ratio with a concomitant decrease in ATP following bilateral carotid artery occlusion in spontaneously hypertensive rats (SHR) and minimal metabolic changes in normotensive rats (NTR), suggesting that the hypertensive rats are more susceptible to cerebral ischemia than NTR. This has been proved by the pathological study which showed more diffuse and severe ischemic lesions of the brain in SHR. 45 Brunner et al. 6 have reported that hypertensive patients with high plasma renin activity (PRA) tend to have more severe vascular complications, such as stroke and myocardial infarction, than patients with normal or low PRA.The present study was undertaken to clarify whether the susceptibility to cerebral ischemia following carotid artery occlusion differs between 2 different varieties of hypertensive rats: renovascular hypertensive rats and desoxycorticosterone hypertensive rats. In both types the duration and grade of hypertension was identical. The RHR rat has high-renin hypertension and the latter (DHR) rats have low-renin hypertension. In these animals, we measured lactate, pyruvate and ATP concentrations in the brain as an indicator of ischemic metabolism and also determined arterial acid-base measurements one hour after bilateral carotid occlusion. Materials and Methods Production of HypertensionMale Wistar rats, weighing 150 to 200 g, were anesthetized with intraperitoneal amobarbital (10 mg/ From the Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.Reprints: Dr. Fujishima, 2nd Dept. of Internal Medicine, Faculty of Medicine, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka City 812, Japan. 100 g body weight). In one group of animals the left renal artery was exposed through a dorsal incision of the abdomen and constricted with a silver clip to 0.2 mm in diameter. The contralateral kidney and its artery were left intact. After the operation, animals were fed with either a regular diet contain...