The pathological changes in the choroid and the retinal pigment epithelium in spontaneously hypertensive rats (SHR) aged 42-117 weeks were observed by transmission electron microscopy. Wistar Kyoto rats (WKY) were also studied as normotensive controls. Some of the endothelial cells of the choroidal arterioles and capillaries were degenerated. Focal cytoplasmic necrosis of the arteriolar smooth muscle cells was seen. The choroid showed severe sclerotic changes, and the retinal pigment epithelium was degenerated with dilated basal infoldings and intracellular vacuoles. Long-term hypertension causes degeneration of the outer retinal layer due to the obstructive changes in the choroidal vasculature.
The effects of near-ultraviolet radiation on choroidal blood flow were studied in aphakic rabbit eyes. After lens extraction, eyes were exposed to monochromatic near-ultraviolet radiation with a wavelength of 365nm and radiant exposure of 8.0J/cm2. Choroidal blood flow was measured by the hydrogen clearance method 3, 7 and 14 days after exposure. Eyes were enucleated after the measurement of choroidal blood flow and examined histopathologically. Choroidal blood flow in the eyes wan significantly reduced 7 and 14 days after exposure compared with control eyes. Histopathologically, the photoreceptors showed marked destruction 3, 7 and 14 days after exposure, while the retinal pigment epithelium and choriocapillaris remained intact during this period. These results suggested that choroidal blood flow was reduced by decreased oxygen consumption in the outer retina as a result of the destruction of photoreceptors after exposure to near-ultraviolet radiation.
We administered the endothelin-A receptor antagonist BQ-123 to spontaneously hypertension rats (SHR) and measured choroidal blood flow (CBF) by the hydrogen clearance method (BQ-123 group, n=8). As a control, we administered saline to SHR (control group, n=8). The BQ-123 group demonstrated a significant increase in CBF throughout the period from 15 minutes until 120 minutes after injection. In contrast, the control group did not demonstrate any increase in CBF. These results suggest that endogenous ET-1 may be involved in the decrease in choroidal circulation of SHR and the administration of BQ-123 may inprove it. Since this change was not detected in Wistar rats, it is considered that ET-1 works more strongly in SHR. It is also presumed that the function of ET-1 varies greatly depending on the internal organs and vasculature.
A study on relationship between the living environment and activities of daily living (ADL) was conducted to all elderly persons of more than 100 years old in 1993. The response was received from 840 males (73.6%) of 100-107 years of ages. Living environment was divided into three areas according to the geographical areas (Hokkaido-Tohoku-Hokuriku-Sanin, Kanto-Tokai-Kinki, and Sanyo-Shikoku-Kyushu), two community types according to an urban or an agricultural or fishing village, and four community sizes according to number of the population. Factors considered to contribute to a high level of ADL were evaluated. The results can be summarized as follows. 1. According to the geographical area, the independence rate (percentage of individuals who were competent for ADL) was significantly higher in Sanyo-Shikoku-Kyushu area than in Kanto-Tokai-Kinki area in all items examined (transferring, feeding, continence and bathing). Regional differences were observed in the state of living, state of medical care, social and cultural activities, and dietary habit since the age of 80 years, watching TV and an interest in health as social and cultural activities were related to high independence rates in areas such as Sanyo. 2. According to the community type, the state of medical care, whether there was a family doctor, social and cultural activities, and dietary habit since the age of 80 years in agricultural and fishing communities appeared to be favorable for independence rate, but there were not observed significant relations. 3. According to the community size, none of the residents in large cities were independent in eating, continence, or bathing. The independence rate of continence was significantly lower than that in small cities and towns or villages in rural districts, suggesting that large cities are an environment unfavorable for socially independent longevity. The household composition, social and cultural activities, and dietary habit since the age of 80 years were different according to the community size, and reading newspapers of social and cultural activities was related to high independence rates in small cities and towns or villages of rural districts.