SUMMARYThe effect of induced hypertension on the blood-brain barrier (BBB) change in Mongolian gerbils exposed to various periods of ischemia was studied. EVANS blue dye was used to determine the BBB change In animals subjected to different levels of hypertension after 3 h ischemia. Horseradish peroxidase (HRP) was used in electronmicroscopic studies of animals subjected to 30 min, 1,3 or 6 h ischemia and subsequently exposed for 30 min to varying periods and sequences of nonno-and hypertension. Furthermore, HRP-labeled vesicle counts were performed in animals from the 30-min ischemia group.Our findings revealed that hypertension, after blood flow restoration following ischemia, induces and/or accelerates BBB damage by enhancing endotheiial vesicular and/or tubuio-channel transport.Stroke, Vol 11, No 6, 1980WHETHER AN INCREASE of blood pressure has a beneficial effect on the ischemic brain is still a matter of debate in clinical studies.1 -* The ischemic brain has been reported to be highly-resistant to blood-brain barrier (BBB) M change which induces vasogenic edema.8 However, it has been reported that a BBB change can occur after restoration of the blood flow to the ischemic brain. "10 The present study was undertaken to determine how a slight change in blood pressure after blood flow restoration might affect the BBB after ischemia, and to elucidate the ultrastructural mechanisms of this BBB change.The results of this line of inquiry may be of clinical importance in managing patients after the surgical restoration of blood flow to ischemic brain, and in the treatment of cerebral apoplexy without angiographic evidence of vascular obstruction 11 '1J and/or with evidence of rich collateral circulation. Materials and MethodsIschemia was produced in adult Mongolian gerbils of either sex under light ether anesthesia by clipping the left carotid artery with Scovill's aneurysmal clip. Polyethylene tubing (PE 10, Clay-Adams, USA) was inserted through the femoral artery to the abdominal aorta of all ischemia-sensitive animals, selected according to previously described criteria."• M Systemic arterial blood pressure was monitored continuously on a Statham transducer. Under pentobarbital anesthesia (1 mg/100 g body weight, i.p.), 0.1-0.5 mg/kg body weight metaraminol bitartrate was repeatedly injected i.v. to maintain the mean arterial blood pressure (MABP) at different levels of elevation. In each animal, MABP was measured at 5 min intervals after blood flow restoration. BBB Change after 3 h Ischemia Demonstrated by Evans Blue PermeabilityAll animals received an i.v. injection of 0.1 ml/100 g body weight of 2% Evans blue dye immediately before clip release. They were sacrificed 5 min to 5 h thereafter by 10% buffered paraformaldehyde perfusion. Abnormal permeability of the BBB to the dye was assessed by visual inspection of coronal blocks of the perfused brains.The animals were divided into 4 groups according to the different levels of MABP (table). Animals were considered to be positive for BBB change when a blue spot ...

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Background-Electrical disconnection of the myocardial extensions into arrhythmogenic pulmonary veins (PVs) is recognized as a curative technique for paroxysmal atrial fibrillation (AF). However, the presence of electrical connections between the PVs, which may make achievement of PV disconnection difficult, has not been systematically evaluated. Methods and Results-Forty-nine consecutive patients with drug-resistant AF underwent ostial radiofrequency (RF) catheter ablation of arrhythmogenic PVs with foci triggering AF. Pacing from inside the targeted PV was performed after each RF delivery to identify the left atrial exit site of the residual venoatrial conduction. Successful PV disconnection was defined as achieving elimination of the PV potentials during sinus rhythm or left atrial pacing, and the loss of left atrial conduction during intra-PV pacing. A total of 112 arrhythmogenic PVs were identified. PV disconnection was achieved with 10Ϯ6.1 minutes of RF delivery to the ostia of 101 targeted PVs. In 7 left superior (LS) PVs from 7 patients (14%), the earliest atrial activity was recorded from the left inferior (LI) PV ostium during intra-LSPV pacing after 11Ϯ4.7 minutes of RF delivery to the LSPV ostium. Disconnection of these LSPVs was achieved by LIPV disconnection. In the remaining 4 PVs from 4 patients, PV disconnection could not be achieved. Conclusions-Fourteen percent of the patients had electrical connections between contiguous PVs. In these patients, ostial ablation of an untargeted PV was required for successful targeted PV disconnection.

Concentrations of [14C]2-deoxy-D-glucose ([14C]DG) and of glucose were measured in plasma of arterial and sagittal sinus venous blood from awake Fischer-344 rats at 3, 12, and 24 months of age, during continuous intravenous infusion of [14C]DG and after a steady-state arterial plasma concentration of [14C]DG was reached. Brain extraction, i.e., the difference between arterial and venous plasma concentrations divided by the arterial plasma concentration, was calculated for both [14C]DG and glucose. Because exchange of both substances between rat plasma and erythrocytes is slow, the ratio of the brain extraction of [14C]DG to that of glucose is identical to the lumped constant in the deoxyglucose procedure of Sokoloff et al. [J. Neurochem. 28, 897-916. (1977)]. This ratio equaled 0.502 +/- 0.015 (SEM) at 3 months, 0.456 +/- 0.007 at 12 months, and 0.418 +/- 0.006 at 24 months of age (n = 15); the means differed significantly from each other (p less than 0.05). The results indicate that the lumped constant declines between 3 and 24 months of age in awake rats, and suggest that many reported age reductions in regional cerebral glucose utilization, of 15-25%, are artifactual.