Five different indices concerning the granularity of renal juxtaglomerular apparatus in the spontaneously hypertensive rat of OKAMOTO and AOKI were determined. HARTROFT'S juxtaglomerular cell granulation index and OKAMOTO'S index were decreased definitely in the hypertensive rats. Index of granularity decreased markedly, while index of hypertrophy and hyperplasia became only slightly smaller. Juxtaglomerular cell count was normal. These findings indicate that the decreased granularity is due mainly to the decrease in granularity of each juxtaglomerular apparatus, and that the numbers of juxtaglomerular cells per apparatus or of juxtaglomerular apparatus per kidney do not differ markedly in the spontaneously hypertensive rats. The results also are in accord with the fact that the activity of the renin-angiotensin system is de-creased in such hypertensive rats.

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Enzyme histochemical studies were performed on the hyhothalamus of spontaneously hypertensive rats (OKAMOTO and AOKI) in the pre-hypertensive stage (40 to 60 days after birth). Each positive finding in spontaneously hypertensive rats was obtained by comparing it to the reaction of normotensive Wistar strain rats with almost the same survival duration. On the other hand, in order to clarify the meaning of the findings thus obtained in spontaneously hypertensive rats, the hypothalamus of normotensive Wistar strain adult rats subjected to various endocrine interferences were similarly examined histochemically and compared with the reaction of the control adult rats. 1) As far as the normal distribution of enzyme activities in the hypothalamus is concerned, acid phosphatase activity was clearly demonstrated in the cytoplasma of nerve cells in contrast with glial substances. Most prominent staining was found in nerve cells of Nucl. paraventricularis and Nucl. supraopticus. Nucl. perifornicalis and Nucl. mamillaris prelateralis were stained relatively deeply. Most of the others were stained moderately. By diphosphopyridine nucleotide diaphorase activity determination, all hypothalamic nuclei showed more or less the activity in the perikaryon of nerve cells. Monoamine oxidase activity was mainly detected diffusely in neuropils and hardly demonstrated in the perikaryon. 2) By enzyme histochemical studies on the hypothalamus of spontaneously hypertensive rats in the pre-hypertensive stage, increase of acid phophatase activity was observed in Nucl. preopticus pars lateralis, Nucl. supraopticus, Nucl. ventromedialis pars anterior, medialis, centralis et lateralis, Nucl. dorsomedialis, Nucl. perifornicalis, Area lateralis hypothalami pars tuberalis, Nucl. arcuatus pars tuberalis et mamillaris, Nucl. posterior hypothalami, Nucl. mamillaris prelateralis, Nucl. supramamillaris and Nucl. mamillaris medialis. Increase of diphosphopyridine nucleotide diaphorase activity was detected in Nucl. premamillaris dorsalis, Nucl. premamillaris ventralis and decrease of the activity was noted in Nucl. arcuatus pars mamillaris and Nucl. mamillaris lateralis. Enhancement of monoamine oxidase activity was observed in Nucl. arcuatus pars tuberalis, Nucl. ventromedialis pars medialis, centralis et lateralis and the activity was reduced in Nucl. suprachiasmaticus and Nucl. mamillaris prelateralis.

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Characteristics of the action potential and stimulus conduction in the A-V nodal region were studied electrophysiologically, especially in connection with the histological findings by means of ultramicroelectrode technique. The intracellular records in each case of normal sinus rhythm and A-V conduction disturbance were obtained. And situation of the tip of the microelectrode was ascertained by using immigration of cobalt ion. The specific muscle fibers were recognized in the vicinity of the A-V node. The action potentials of those fibers represented an inter-mediate type between the nodal type and the ordinary atrial muscle type. When the recording microelectrode was moved from the upper part of the node to the His' bundle, the shape of the action potential changed from the typical nodal type to the His' type, and the onset of the activation was gradually delayed. Disturbances of the A-V conduction were made using the effects of acetylcholine. And incomplete A-V block, complete A-V dissociation, and A-V dissociation with nodal or ventricular capture were observed and the boundary of characteristic changes of the action potential in all cases was found at the atrial margin of the A-V node which is netlike in structure.

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Mechanism of the metabolic disturbance as the cause of the experimental hypertension was further studied in this report. Using the heart and skeletal muscle of toad, the author demonstrated that dinitrophenol and monoiodoacetate induce the accumulation of Na ion in the muscle cells. Here neurogenic factor of hypertension was also examined and discussed.

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Thus far, we have reported electrocardiographic patterns of several congenital heart diseases in relation to operative findings, and discussed about some points of differential diagnosis.

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[in Japanese]

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