Increased adrenal epinephrine and norepinephrine in spontaneously hypertensive rats treated with hyperbaric oxygen

Abstract

ウィスター京都ラット(WKY), 高血圧自然発症ラット(SHR), 高血圧自然発症脳卒中易発症ラット(SHRSP)を5群に分け, 6週齢より13週齢まで以下のごとぎ実験操作を連日施行した.第1群は対照群, 第皿群は大気下における絶対圧2気圧の高圧酸素処置群, 第皿群は高濃度酸素環境下における高圧酸素処置群, 第W群はhydralazine投与群, 第V群は1%飲料食塩水投与下における副腎別除群である.第1群のSHR, SHRSPの副腎中のエピネフリン(E), ノルェピネフリン(NE)含量は同群のWKYのぞ治より高値であった(P<0, 05-Pく0.001).同様の傾向が副腎E含量についても認められた.第ll, 皿群のSHR, SHRSPの副腎E・NE含量は第1群のSHR, SHRSPのそれよりそれぞれ高値を示した(P<0.05～P<0.001).しかし両群間のstrainmatchedhypertensiveratsの血圧は同レベルであった.副腎別除術(V)はどのratstrainにも有意の血圧変動を惹起させなかった.hydralazine(N)投与はSHR, SHRSPの血圧を低下させたが, 副腎E・NE含量に有意の影響を与えなかった.以上の成績より, SHR, SHRSPの副腎髄質機能が高圧酸素処置により充進することが証明された.また同時に, 副腎髄質機能の充進がこれらの動物の高血圧のpathogenesisとほとんど無関係であることが判明した.

Adrenal catecholamines were determined in Wistar Kyoto rats (WKY), and stroke-prone and stroke-resistant spontaneously hypertensive rats (SHRSP, SHR) treated with hyperbaric oxygen for 90 minutes daily from 6 to 13 weeks of age. The animals were divided into 5 groups. Group I (control group), was handled under the same conditions as pressure-treated groups II and III, but with ambient oxygen pressure and concentration. Group II (pressure-control group), was treated with 2 atmospheric absolute pressures (ATA) of air without any oxygen provided. Group III (high-oxygen group), was exposed to 2 ATA under the environment of air saturating oxygen. Group IV (antihypertensive group), was treated with hydralazine. Group V (adrenalectomized group), was given 1% NaCl solution and bilateral adrenalectomy. The average contents of adrenal norepinephrine of SHR and of SHRSP in Group I were greater (p less than 0.05-p less than 0.001) than those of the WKY in Group I. A similar tendency was also observed for the content of adrenal epinephrine. The average concentrations of adrenal epinephrine and norepinephrine of SHR and SHRSP in Group II and III were significantly (p less than 0.05-p less than 0.001) greater than those of the respective rats in Group I, but no significant differences were noted in the blood pressure between pressure-treated groups (II, III) and the control group (I). Adrenalectomized SHR, SHRSP and WKY rats (Group V) had similar blood pressure levels as the control rats (Group I). The development of hypertension in SHR and SHRSP was effectively suppressed by the treatment with hydralazine, which, however failed to reduce concentrations of adrenal epinephrine and norepinephrine in these rats. These results indicate that increased adrenomedullary function in SHR and SHRSP is further enhanced by hyperbaric oxygenation treatment, but that high concentrations of adrenal catecholamines are not required for the pathogenesis of spontaneous hypertension of these animals at this age.