EFFECT OF INTRACAROTIDLY INFUSED PLATELET-ACTIVATING FACTOR ON FELINE CEREBROCORTICAL BLOOD FLOW

1993 Fiscal Year Final Research Report Summary

• Project/Area Number: 04670496
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Neurology
• Research Institution: KEIO University
• Principal Investigator: TANAHASHI Norio Dept.of Internal Medicine, Keio University, assistant Professor, 医学部, 講師 (10124950)
• Co-Investigator(Kenkyū-buntansha): SHINOHARA Tamotsu Dept.of Internal Medicine, Keio University, Instructor, 医学部・内科, 助手 (50138004) ; KOBARI Masdahiro Dept.of Internal Medicine, Keio University, Instructor, 医学部・内科, 助手 (30162035)
• Project Period (FY): 1992 – 1993
• Keywords: Platelet-activating factor(PAF) / cerebral blood flow(CBF) / photoelectric method / cerebral blood volume(CBV) / cerebral cortex / systemic arterial blood pressure(SABP) / veactive hyperemia / mean transit time

Research Abstract

An increasing number of reports have suggested the possible involvement of the platelet-activating factor (PAF) in processes associated with cerebral ischemia and neurotrauma. The purpose of the present study was to examine the effect of intracarotidly infused PAF on the cerebrocortical blood flow.
Materials and Method : Seven cats were anesthetized and artificially ventilated. The left femoral and lingual arteries were cannulated. They were used to monitor the systemic arterial blood pressure (SABP) and to inject carbon-black (CB) solution into the carotid artery, respectively. A photoelectric apparatus (Am J Physiol 235 : H56-H63, 1978) was attached to the left parietal cortex, and the cerebral blood volume (CBV) and mean transit time of blood through the cortical tissue (MTT) were measured. The cerebral blood flow (CBF) was calculated form the CBV and the MTT of blood by applying the Stewart-Hamilton equation and cerebrocortical vascular resistance (CVR) was further calculated using the formula, mean arterial blood pressure (MABP)/CBF.PAF (0.01g/kg) suspended in 0.25% bovine serum albumin in 1 ml of saline was infused into the left carotid artery within 15s. Result : Immediately after the PAF administration, the mean arterial blood pressure (MABP) decreased form 125(〕SY.+-.〔)20 to 107(〕SY.+-.〔)18 mmHg (p<0.05) and returned to the previous level in 5 min (130(〕SY.+-.〔)17mm Hg). CBV remained constant throughout ; i.e., before (6.3 vol%), immediately after (6.0(〕SY.+-.〔)0.3%), and 5 min after the administration (6.4(〕SY.+-.〔)0.5 vol%). MTT was increased immediately after the PAF administration from 5.9(〕SY.+-.〔)2.1 to 8.3(〕SY.+-.〔)3.4 s (p<0.05) and returned to the previous level in 5 min (5.6(〕SY.+-.〔)1.9 s). CBF was decreased immediately after the PAF administration from 73(〕SY.+-.〔)29 to 51(〕SY.+-.〔)21 ml/100g brain/min (p<0.01) and returned to the previous level in 5 min (76(〕SY.+-.〔)24 ml/100g brain/min). CVR was increased immediately after the PAF administration from 1.92(〕SY.+-.〔)0.47 to 2.36(〕SY.+-.〔)0.74 mmHg/ml/100g brain/min (p<0.05) and returned to the previous level in 5 min (1.92(〕SY.+-.〔)0.43 mmHg/ml/100g brain/min). Conclusion : Intracarotidly infused PAF momentarily decreased the cerebrocortical blood flow.