We measured local cerebral blood flow over 24 hours in 10 unanesthetized, freely moving rats to determine whether blood flow in the hippocampus fluctuated as a function of time of day. We measured hydrogen clearance at 1-hour intervals using a polyurethane-coated platinum electrode with a 1-mm bare tip implanted in the dorsal hippocampus. Individual rats displayed a wide range of local cerebral blood flow values (from 30 to 100 ml/min/100 g tissue) in a day. In seven of the 10 rats, the overall mean hippocampal blood flow for the dark cycle (7 PM-5 AM) was significantly (p<0.001, 0.01, or 0.05) greater than that for the light cycle (6 AM-6 PM), showing an average increase of 20%. Further, the maximum mean hippocampal blood flow at 11 PM in all 10 rats was 42% greater than the minimum at noon. Our study demonstrates for the first time that local cerebral blood flow in the hippocampus shows diurnal variation. (Stroke
A 65-year-old female with Barrett epithelization was reported. She suffered from esophagitis accompanying hiatal hernia. A Thirteen-centimeter wandering of the esophagogastric junction within five years was detected by following-up esophagoscopic examination.
Studies were carried out to investigate central actions of vasoactive intestinal polypeptide (VIP) and neurotensin (NT) on systemic blood pressure (BP), heart rate (HR) and salivary secretion in urethane-anesthetized male rats. Intraventricular (i.c.v.) administration of VIP caused dose-related increases in BP, HR and salivary secretion. Nearly maximum values were obtained at the dose of 2.0 micrograms for BP and 10.0 micrograms for salivary secretion, whereas the increase in HR did not attain the maximum even with the dose of 10.0 micrograms. Administration of hexamethonium (i.v.) completely blocked the increasing response of BP and HR, and the administration of pimozide (i.p.) or phenoxybenzamine (i.v.) reduced them. The increasing response of salivary secretion was almost completely blocked by all of the drugs. The administration of NT (i.c.v.) produced no change in the BP, HR and salivary secretion. The present results indicate that, 1) centrally administered VIP may somehow augment the sympathetic nerve discharge and/or adrenal medulla secretion, and 2) central VIP may play a role in the control of salivary regulation, probably through sympathetic nerves.
Studies were carried out on the role of vasoactive intestinal polypeptide (VIP) in the regulation of secretion and blood flow in the rat salivary gland. The first experiments to investigate the spontaneous secretory pattern revealed a clear diurnal fluctuation with a significant increase at night, so that the subsequent experiments were performed during the daytime where the secretion was consistently low.Intravenous administration of VIP at a dose smaller than40pmole caused a dose-dependent vasodilatory response, but at a high dose such a local effect was hampered by a decrease in systemic blood pressure. VIP potentiated the acetylcholine chloride (AcCho)-evoked salivary secretion, but VIP (0-100pmole/ kg) alone did not cause salivary secretion.Atropine reduced the salivary secretion evoked by AcCho and VIP, and the blood flow change evoked by AcCho. However, the blood flow change evoked by VIP was not affected by atropine.Hexamethonium exerted no significant effect on the response to administration of AcCho or VIP. The results indicate that VIP has a significant vasodilatory action and cooperates with AcCho in the regulation of salivary secretion in the rat, and VIP effects are atropine resistant, as in other species of animals.
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