Michiya Ohtaka

Cardiac Hypertrophy in Early Hypertension

Studies of cardiac hypertrophy in spontaneously hypertensive rats have indicated that left ventricular hypertrophy occurred even in the prehypertensive stage. These findings suggested that other factors besides blood pressure levels, and including possibly a genetic predisposition to myocardial hypertrophy, could play a role in structural cardiovascular alterations in spontaneously hypertensive rats. More recent studies have confirmed these anatomic results; left ventricular hypertrophy was vectorcardiographically detected even in the prehypertensive stage in voth young stroke-prone rats and stroke-resistant spontaneously hypertensive rats. Further, a close relation was found between degree of left ventricular hypertrophy and vascular hypertrophy or hyperplasia; this suggests that early detection of left ventricular hypertrophy may be a useful indicator of the incipient stage of structural vascular changes in genetic hypertension.

Interrelationships between blood pressure, sodium, potassium, serum cholesterol, and protein intake in Japanese.

Interrelationships among blood pressure (BP), sodium (Na), potassium (K), dietary protein, and serum cholesterol level (Chol) were examined in 62% (1120) of 1818 Japanese inhabitants of both sexes aged over 30 years who lived in a rural village in Japan. Fasting single-spot urine specimens were collected in the morning to measure Na, K, urea nitrogen (UN), inorganic sulfate (SO4), and creatinine (Cr). The Cr ratios of Na, K, UN, SO4, Na/K, and SO4/UN were analyzed by multiple regression analysis to determine independent associations with BP together with age, obesity index, hematocrit (Hct), Chol, triglyceride (TG), and fasting serum glucose level (Glu). Except for Na/Cr in men, Na/Cr and Na/K were found to be independently and positively related to BP, particularly to systolic BP (SBP). In contrast, K/Cr and SO4/UN (an index related to the dietary score of sulphur-containing amino acids derived mainly from animal protein) were both negatively associated with SBP, and UN/Cr (an index of total protein intake) was positively associated with SBP in men. Chol was linked to BP negatively in men but positively in women. Age, obesity index, TG, and Hct were generally positively and significantly related to BP in both sexes. The results confirmed on epidemiological grounds the positive link of Na and the negative link of K to BP within a single population in Japan. They further suggest, although only in men, that there is a negative relationship of Chol and dietary animal protein with BP.

Pathogenic Mechanisms and Prevention of Stroke in Stroke-prone Spontaneously Hypertensive Rats

Publisher Summary The establishment of stroke-prone spontaneously hypertensive rats (SHRSP), of which more than 80% died of stroke, has led to extensive study on the mechanisms of cerebrovascular lesions. Studies have revealed that hypertension is the most important systemic factor for stroke. Other possible factors are the alteration of the physical characteristics of the arterial wall, and involvement of humoral factors such as renin. Further, the angioarchitectural studies have clarified that the predilection sites of stroke are the boundary zone of the three main cerebral arterial supplies and the areas fed by recurrent arteries. This chapter presents the assay of norepinephrine in the brain quantitatively or by fluorescent histochemical methods. regional cerebral blood flow (rCBF) tends to increase under hypertensive state below 200 mm Hg but decreases abruptly in SHRSP with severe hypertension over 220 mm Hg.

Effect of Sympathectomy on Cerebrovascular Fat Deposition in Renal Infarction Hypertensive Rats

No effect was observed on cerebrovascular atherogenesis after cervical sympathectomy in renal infarction hypertensive rats. These results suggest that denervation has no effect on atherogenesis in renal infarction hypertensive rats and the role of the nervous system is more important in the development of fat deposition in SHRSP which show greater susceptibility to genetic hypertension and atherogenesis

Hypertension, Stroke and Atherogenesis in Experimental Models

By the establishment of proper animal models for hypertension, stroke, and ath-erogenesis, it has been possible to greatly accelerate studies on not only the pathogenesis but also the interrelation of these pathologic states.