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Biomedical subjects

I Nishio

Publications and source records attributed to I Nishio.

At least 199 records · Page 11Linked to original sources
PubMed1983

Changes in plasma norepinephrine after intravertebral artery infusion of saralasin in sodium depleted dogs.

This study was designed to investigate the central action of circulating angiotensin II on the regulation of blood pressure in sodium depleted states. The effects of intravertebral arterial infusion of angiotensin II and [Sar-1, Ala-8] angiotensin II (saralasin) on plasma norepinephrine (NE) were studied in alpha-chloralose anesthetized dogs. Intravertebral arterial infusion of angiotensin II (10 ng/kg/min) increased mean arterial pressure (MAP), heart rate (HR) and plasma NE. Plasma NE was decreased by intravertebral arterial infusion of saralasin (0.40 +/- 0.05 to 0.28 +/- 0.04 ng/ml, p less than 0.05) in normal dogs. The administration of furosemide produced significant increases in plasma NE (142.4 +/- 23.7%, p less than 0.01), plasma renin activity (PRA) (158.6 +/- 26.3%, p less than 0.01) and HR (32.3 +/- 6.0 beats/min, p less than 0.01). A slight rise in mean blood pressure (3.9 +/- 1.2 mmHg, p less than 0.05) was observed during the furosemide administration. Saralasin infused into the vertebral artery significantly suppressed the furosemide-induced increases in plasma NE, HR and PRA, and lowered mean arterial blood pressure. Intravenous infusion of the same dose of saralasin produced no changes in arterial blood pressure, HR and plasma NE. These results suggest that the central sympathetic potentiation induced by circulating angiotensin II may contribute to the regulation of blood pressure in sodium and volume depleted states produced by furosemide.

Aldosterone↗
PubMed1983

Phase separation in rat lenses cultured in low glucose media.

Experimental evidence that indicates the nuclear opacity that develops in the hypoglycemic cataract in rat lenses is the result of a phase separation of the lens cytoplasm is presented. Phase diagrams of the cytoplasm of organ-cultured lenses were constructed for a series of incubation times in normal and hypoglycemic media. In normal media, the maximum phase separation temperature, Tmax, of the lens cytoplasm decreases with time. In hypoglycemic media, Tmax increases with time and exceeds 37 C after 24 hrs. The increase in Tmax can be stopped and reversed if the lens is returned to normal media within 8 hrs; in good agreement with an earlier biochemical analysis of the kinetics of hypoglycemic cataract formation.

Animals↗
PubMed1981

Changes in cardiac beta-adrenoceptor concentrations in spontaneously hypertensive and experimental renal hypertensive rats.

Cardiac beta-adrenoceptors were studied in membrane fractions from spontaneously hypertensive rats (SHR) and rats with two-kidney, one clip hypertension (2K, 1C HT), using radioligand binding method. beta-Adrenoceptor concentration measured by [3H]-dihydroalprenolol (DHA) binding was significantly lower in cardiac membranes from two months old SHR than those from Wistar-Kyoto rats (WKY) (38.2 +/- 2.6 vs 45.1 +/- 1.8 fmol/mg protein, means +/- SEM, p less than 0.05). Cardiac membranes from 2K, 1C HT rats had also a lower concentration of beta-adrenoceptors than those from the sham-operated control rats at a week after operation (30.9 +/- 2.2 vs 47.8 +/- 1.6 fmol/mg protein, p less than 0.01). But receptor affinity remained unchanged. These reduced concentrations of beta-adrenoceptors were restored to control levels at 12 months old in SHR and at 6 weeks after operation in 2K, 1C HT rats, although age-dependent decrease in beta-adrenoceptor was observed. The decrease in beta-adrenoceptor was associated with increase in plasma noradrenaline levels during the earlier stages of hypertension. But there is no correlation between beta-adrenoceptor concentrations and plasma noradrenaline levels in the chronic stages of hypertension. No significant difference was found in activities of 5'-nucleotidase, which is a marker enzyme of cell membrane, in membrane fractions between the hypertensive hearts and the controls, suggesting that the cardiac hypertrophy is not a determinant factor for change in beta-adrenoceptor. The observed decrease in beta-adrenoceptor concentration may reflect an increase in sympathetic nerve activity during development of hypertension. In the chronic stages of hypertension, additional factors may be involved in the restoration of beta-adrenoceptors.

5'-Nucleotidase↗
PubMed1980

The effect of angiotensin II antagonist, Sar1-Ile8-angiotensin II, on furosemide-induced increase in plasma noradrenaline, renin activity and aldosterone in unanesthetized dogs.

In order to evaluate the role of the renin-angiotensin system and the sympathetic nervous system in the maintenance of blood pressure in the sodium-depleted state, the changes of plasma renin activity (PRA), plasma aldosterone concentration (PAC) and plasma noradrenaline (PNA) were examined in unanesthetized dogs after the administration of furosemide. Furthermore, the role of the renin-angiotensin system in the increased sympathetic nerve activity induced by furosemide was assessed by using Sar1-Ile8-angiotensin II, an angiotensin II antagonist. When a dose of 0.8 mg/kg of furosemide was injected intravenously, 3 times every 15 minutes, PRA and PNA were significantly increased with a concomitant increase in PAC. Sar1-Ile8-angiotensin II induced a significant increase in PAC and a slight increase in PRA, while no changes were found in PNA and the mean blood pressure. The increase in PNA induced by furosemide was inhibited dose-dependently by Sar1-Ile8-angiotensin II, through PRA and PAC were further increased. There results suggest that an administration of furosemide induced the increase in PNA and the increase in PNA by furosemide might by mediated by the renin-angiotensin system.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1979

Noradrenaline clearance in hypertensive patients with various degrees of renal function.

1. Hypertensive patients with normal renal function showed significantly higher plasma urinary noradrenaline than the normotensive controls, and the hypertensive patients with mild to moderate disturbance of renal function showed the same noradrenaline concentration as the controls. 2. Hypertensive patients with severe renal function disturbance showed significantly higher plasma noradrenaline concentrations and lower urinary noradrenaline excretion than the controls. 3. Noradrenaline clearance calculated by free plasma noradrenaline and total urinary noradrenaline was significantly decreased in those subjects with severe renal dysfunction. 4. Conjugated plasma noradrenaline was increased in the hypertensive patients with the severe disturbance of renal function, and conjugated urinary noradrenaline increased in those without severe renal dysfunction.

Adult↗
PubMed1979

Cytoplasmic phase separation in formation of galactosemic cataract in lenses of young rats.

We have determined the age dependence of the characteristics of the cytoplasmic phase separation of lenses from normal and galactosemic young rats. In the normal lens, the temperature at which the phase separation occurs decreases monotonically with age. In the lenses of rats fed with a high galactose diet, the phase separation temperature becomes increasingly higher with the development of galactosemia. When the phase separation temperature becomes higher than the ocular temperature, the nuclear opacity appears in vivo. The opacity is the result of light scattering by spatial fluctuations of the refractive index formed by interspersed regions of two separated phases in the fiber cell cytoplasm. This shows that the nuclear opacity that develops in the lens of galactosemic rats is the manifestation of phase separation of the lens fiber cytoplasm.

Journal Article↗
PubMed1979

Plasma catecholamines determination using high pressure liquid chromatography and their roles in blood pressure regulation and experimental hypertension in rats.

Plasma catecholamine levels have been used experiemtally and clinically as the indices of the sympathetic nerve activity. We measured plasma catecholamines using high pressure liquid chromatography in rats to assess the significance of plasma catecholamines as an index of the sympathetic nerve activity and its role in hypertension. Pentobarbital anesthesia depressed plasma catecholamine levels, especially plasma adrenaline. Sodium loading for 5 weeks suppressed plasma noradrenaline, while administration of furosemide (1 mg/kg) produced the elevation of plasma noradrenaline. Experimental hypertension, one-kidney and two-kidney types of Goldblatt hypertension and DOCA-salt hypertension, raised plasma noradrenalines both in acute and chronic phases. The infusion of pressor doses of angiotensin II suppressed plasma noradrenaline by the reflex mechanism. Sar1, Ile8-angiotensin II and SQ 14,225 did not suppress plasma cathecholamine elevation due to hemorrhage. L-Hydroxyldopamine produced elevation of plasma catecholamines in experimental nypertension and controls in rats. After adrenal demedullation, plasma noradrenaline was decreased by the administration of 6-hydroxy-dopamine. Acute reduction of circulating blood volume and blood pressure fall produced the elevation of plasma catecholamine, especially plasma adrenaline. In rats, the adrenal medulla plays an important role in the regulation of blood pressure.

Aging↗
PubMed1979

The evaluation of plasma dopamine beta-hydroxylase activity in essential and secondary hypertension.

The relation of plasma dopamine beta-hydroxylase (DBH) activity to age was examined in normotensive and hypertensive subjects. Plasma DBH activity was the highest in the group of 25--34 years and gradually decreased with age. Plasma DBH activity was higher in the hypertensives than in the normotensives in all age groups, and the difference was significant between the groups of 45--54 and 55--64 years. Plasma DBH activity was increased in labile hypertension. Plasma DBH activity was higher in the group of essential hypertension with normal renal function than in that with reduced renal function. It was lower in the severe hypertensives than in the mild cases. Plasma DBH activity was also decreased in the hypertensive patients with cerebrovascular disorders. Plasma DBH activity was lower in the hypertensive patients with renal parenchymal diseases than those of essential hypertension with normal renal function. Plasma DBH activity was also decreased in primary aldosteronism, while it was increased in pheochromocytoma. These observations suggest that measurement of plasma DBH activity may be valuable in the differentiation of essential hypertension from the secondary forms of hypertension, and the evaluation of the hypertensive processes. To evaluate plasma DBH activity, it is important to consider its age-related changes.

Adult↗
PubMed1977

Hypertensive changes in experimental nephritis combined with experimental hypertension.

The role of hypertension in chronic glomerulonephritis was studied in rats with experimental hypertension and nephrotoxic serum nephritis. Nephrotoxic serum nephritis accelerated the hypertensive course of Godblatt's type of experimental hypertension both in the acute and chronic phases. Malignant hypertension was found to be caused in some rats by the nephrotoxic serum injection in the chronic phase of experimental hypertension. Nephrotoxic serum nephritis was more protracted in SHR than in control rats. These results suggest that hypertensive changes might aggravate glomerulitis, and that nephritic processes also facilitate the hypertensive changes.

Animals↗