Hisaichi Sakuma

Exocytosis plays an important role in catecholamine secretion from human pheochromocytoma.

Plasma dopamine beta-hydroxylase (DBY) activity, urinary catecholamine (CA) and vanillylmandelic acid (VMA) were studied pre- and postoperatively in 20 patients with pheochromocytoma. Preoperative plasma DBH activities were distributed widely, ranging from normal to very high; the mean value of DBH as well as urinary CA and VMA was significantly greater than that of normal subjects. Postoperative falls of plasma DBH activity, of urinary CA and of VMA were by 76%, 96% and 83% of the preoperative level, respectively. Significant correlations were observed between postoperative falls of individual DBH activities, urinary VMA and weight of the tumors, whereas there was correlation neither between preoperative DBH activity and urinary CA, nor between the rate of postoperative falls of these respective values. These findings suggest that pheochromocytoma is capable of secreting DBH, and wide variations in the rate of DBH output from these tumors may account for varying capacity of CA biosynthesis in the tumor. Further, it may be concluded that the process of exocytosis plays an important role in the mode of CA secretion by these tumors, although secretion through diffusion may be operating as well.

Norepinephrine levels in the coronary sinus in patients with cardiovascular diseases at rest and during isometric handgrip exercise

In order to evaluate cardiac sympathetic nerve activity, plasma norepinephrine levels in the coronary sinus (NECS) and in the artery (NEA) were determined in 24 subjects with cardiovascular diseases and in six with functional murmur. The resting NECS was greater than NEA in 14 subjects with normal left ventricular end-diastolic pressure (LVEDP) (p < 0.001) and/or in 22 with normal cardiac index (p < 0.04), whereas NECS was not significantly different from NEA in the remaining patients with elevated LVEDP and/or with reduced cardiac index. Isometric handgrip exercise increased both NECS and NEA (p < 0.001). When subjects were divided into two groups according to the slope of the ventricular function curve (delta stroke work index/delta LVEDP), NECS during exercise was greater then NEA in the group having slopes of 1.0 or more (p < 0.01), but neither values significantly differed in the group with slopes of less than 1.0. In the latter group, cardiac NE overflow rat calculated from the difference between NECS and NEA multiplied by coronary sinus plasma flow, was significantly less than that of the former group before and during handgrip (p < 0.05 and p < 0.01, respectively). These results suggest that cardiac norepinephrine release into the coronary sinus is reduced in patients with impaired cardiac function.

A CASE OF AUTONOMIC HYPERREFLEXIA: WITH SPECIAL REFERENCE TO THE DISTURBANCES IN THE CARDIOVASCULAR REGULATION

結核による脊椎破壊のため,頚髄以下の脊髄横断症状および特異な血圧異常を併発した症例を呈示し,併せて本症における交感神経機能について検討を加えた.症例は53才の女子で,肺および脊椎結核のため, 20年来療養を続けてきたが, 1～2年前から著明に動揺する高血圧を認め,また,上半身を起こすと急峻な血圧低下を来たし,時にショック症状を呈した.昇圧発作は,膀胱内圧の上昇や麻痺部に対する寒冷・触刺激により容易に誘発され,ノルエピネフリン(NE)静注に対して過大な昇圧反応を示した. 24時間尿中カテコラミンおよびVMA排泄量は正常下界値を示した.血中NE濃度は血圧の変化と有意の相関を示したが,いずれも低値ないし正常範囲内の値であつた.血中エピネフリン濃度および血清dopamine-β-水酸化酵素活性はともに低値を示し,血圧との間に有意の相関は認められなかつた.本例に認められた高血圧発作および体位性低血圧はともに少量のフェノキシベンザミンの投与により著明に抑制された.本症は,交感神経系が中枢性および末梢性機序により,循環機能の維持に重要な役割を担つていることを明示するが,これらの交感神経機能の異常を検索する上で,血中カテコラミン濃度は最も信頼性の高い指標と考えられた.