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Biomedical subjects

E Higashihara

Publications and source records attributed to E Higashihara.

At least 109 records · Page 6Linked to original sources
PubMed1985

Effects of aldosterone on potassium recycling in the kidney of adrenalectomized rats.

Recent studies have suggested that potassium, like urea, undergoes medullary recycling. The present cortical and papillary micropuncture studies were designed to confirm the existence of medullary potassium recycling and to determine whether acute infusions of aldosterone affected this phenomenon. Thus, nephron segmental analysis of potassium and sodium transport was conducted in adrenalectomized Munich-Wistar rats and similarly prepared rats that received aldosterone acutely to achieve physiological blood levels. The clearance results demonstrated that aldosterone has an acute antinatriuretic and a kaliuretic effect, whereas the micropuncture studies demonstrated that 1) aldosterone increases potassium secretion between early and late distal tubule punctures; 2) aldosterone causes an increase in delivery of potassium to the papillary collecting duct; 3) aldosterone does not increase potassium secretion across the papillary collecting duct; and 4) aldosterone significantly increases medullary potassium recycling as evidenced by increased quantities of potassium present at the bend of the loop of Henle in response to aldosterone infusions. Thus, the studies confirm the existence of potassium recycling and suggest that this phenomenon is a feedback system that, in part, regulates urinary potassium excretion.

Adrenalectomy↗
PubMed1984

Experimental study on the pulmonary absorption and excretion of toluene.

Three exposure levels of toluene were inhaled by dogs for 1 h. Toluene concentrations in expired air, arterial blood and venous blood were repeatedly measured. Absorptions of toluene within one hour of exposure were 25, 56 and 74 mg/kg at 700, 1500 and 2000 ppm respectively (absorption ratio = 27%). The cumulative excretion one hour after exposure was 63% of the absorped material at all three exposure levels. Multiple regression analyses were performed to interconnect the independent variables.

Absorption↗
PubMed1984

Unilateral and segmental medullary sponge kidney: renal function and calcium excretion.

The renal acidification defect and renal hypercalciuria have been reported in patients with pan-renal and bilateral medullary sponge kidney. However, little is known about patients with unilateral or segmentally affected medullary sponge kidney. We report 2 cases of partially affected medullary sponge kidney with normal acidification ability and normal urinary calcium excretion, although the ability to concentrate urine was diminished. These findings suggest that in patients with partially affected medullary sponge kidney nephrolithiasis is not the consequence of renal hypercalciuria induced by systemic acidosis but is owing to the urinary stasis caused by cystic dilatation of the terminal collecting duct.

Adult↗
PubMed1984

Medullary sponge kidney and renal acidification defect.

Medullary sponge kidney ( MSK ) is one of the entities which comprises a subclass of renal cystic disorders. While the clinical signs, symptoms, and radiological findings have been well documented in the past, the literature concerning renal function in these patients is relatively sparse. Thus, the purpose of the present studies was to examine the renal function in 11 patients with MSK and compare them to seven healthy volunteers and ten control patients with bilateral renal stones. Patients with MSK had normal GFR, RPF, and capacity to dilute urine; however, their urine concentrating ability was diminished. Urine pH in MSK patients was higher than in control patients with NH4Cl administration, while titratable acid excretion was lower than normal. Steady-state plasma bicarbonate concentration was lower in MSK patients than in controls but arterial pH was within normal limits. These studies suggest that MSK patients have defects in urinary acidification and concentration mechanism which may, in part, be the result of functional abnormality of the terminal collecting ducts.

Acid-Base Equilibrium↗
PubMed1984

Aldosterone effects on papillary collecting duct pH profile of the rat.

A number of recent studies have suggested that the medullary and papillary collecting ducts possess a high capacity for bicarbonate reabsorption. Because 3H binding studies have suggested the presence of mineralocorticoid receptors along the papillary collecting duct and because clearance studies have suggested that aldosterone affects urinary acidification, we designed a series of clearance and micropuncture studies to examine the role of the papillary collecting duct in final urinary acidification. The studies were conducted in intact and adrenalectomized rats receiving either replacement glucocorticoids alone or glucocorticoids with acute infusion of physiological doses of aldosterone. The results show that under normal acid-base status all rats had a pH profile along the papillary collecting duct with more terminal portions being more acidic than the proximal portions. This decreasing pH profile was diminished in acidotic adrenalectomized rats but returned to normal with acute administration of aldosterone. In all cases the luminal potential difference was slightly positive and did not change with adrenalectomy or administration of aldosterone. These results demonstrate that the papillary collecting duct participates in the generation of maximal urinary pH gradient and that this process is partly influenced by aldosterone.

Adrenalectomy↗
PubMed1984

[An experimental examination of extra-hepatic metabolism of trichloroethylene in dogs].

To investigate the extra-hepatic organs metabolism of trichloroethylene, the extra-hepatic circulation in dogs was established by operating on the portal vein-right femoral vein bypass and other locations. These dogs were exposed for one hour to trichloroethylene at concentrations of 700 ppm. Metabolite (trichloroethanol (F-TCE), trichloroacetic acid (TCA) and total trichloroethanol (T-TCE) changes in serum and urine were measured from the beginning of exposure until one hour after termination, and compared with previous data as control. The following results were obtained. This operation method gave a very slight invasion on dogs. About two hours after the operation, no abnormal findings were observed clinically or physiologically. This method was considered to be one of the best for study of the metabolism of chemical substances in the extra-hepatic organs of dogs. The produced ratios of F-TCE, TCA and T-TCE in extrahepatic organs were about 60, 10 and 30% exposure to trichloroethylene at 700 ppm, respectively.

Animals↗
PubMed1983

[Uptake, elimination and metabolism of tetrachloroethylene in dogs].

Fifteen dogs were made to inhale tetrachloroethylene at concentrations of 700, 1,500, 2,000 ppm for one hour, and the changes in its concentrations in the expired air, the arterial blood, the venous blood and its metabolites (trichloroacetic acid (TCA), free-trichloroethanol (F-TCE) ) in the serum and the urine were measured from the beginning of exposure until two hours after it had been terminated. The results obtained were as follows. Levels of cumulative intake of tetrachloroethylene after one hour (i.e., at the termination of the inhalation) were 47 mg/kg for 700 ppm, 79 mg/kg for 1,500 ppm and 103 mg/kg for 2,000 ppm. Mean cumulative excretion ratio against the total intake two hours after the termination of the inhalation was 69% as the average for the three exposure levels. Mean ratio of the total absorption to the total intake for one hour was 23% as the average for the three levels. Using the above results, the authors did the multiple regression analysis of cumulative absorption (Y1) as well as cumulative excretion (Y2) taking two independent variables (X) and (Insp. or Z), which are as follows. a) During the exposure period, Y1: cumulative absorption (mg/kg), X1: exposure duration (min), Insp.: levels of solvent value in the inspired air (microgram/ml), log Y1 = -2.2819 + 0.5681 log X1 + 0.8232 log Insp. b) During the post exposure period, Y2: cumulative amounts of solvent excreted (mg/kg), X2: time in minutes after exposure end (min), Z2: cumulative absorption when exposure ended (mg/kg), log Y2 = -2.016 + 0.6976 log X2 + 0.7397 log Z2.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗