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Biomedical subjects

T Sanaka

Publications and source records attributed to T Sanaka.

At least 55 records · Page 3Linked to original sources
PubMed1990

Clinical profile of Japanese dialysis patients with diabetic nephropathy, diagnosed as having diabetes before the age of thirty.

Diabetic nephropathy is the leading cause of death in young diabetic patients. There are a large number of patients with non-insulin-dependent diabetes mellitus (NIDDM) who are diagnosed before the age of 30 in Japan. We investigated 36 patients with young-onset diabetes who started dialysis between 1978 and 1987 in our hospital. Of the 36 patients, 12 (33.3%) were classified as having insulin-dependent diabetes mellitus (IDDM), 22 (61.1%) had NIDDM, and 2 (5.6%) could not be classified clinically. The percentages of the different types of diabetes in our series of dialysis patients were almost identical with those in Nagai's series of 551 diabetic patients diagnosed before the age of 30 at the Diabetes Center of Tokyo Women's Medical College from 1976 to 1981. The present study showed the young-onset NIDDM in Japan was associated with almost the same incidence of end-stage diabetic nephropathy as was IDDM. However, the number of NIDDM patients diagnosed under 30 years of age was almost double that of IDDM patients. Thus, we have to pay greater attention to the development of diabetic nephropathy in young-onset NIDDM patients than has been thought necessary in the past.

Adolescent↗
PubMed1990

Renal and hemodynamic effects of endothelin in anesthetized dogs.

The effects of endothelin on systemic hemodynamics and renal functions were investigated in anesthetized dogs. Infusion of endothelin at a dose of 1 ng/kg/min decreased renal blood flow and increased renal vascular resistance and filtration fraction. Endothelin at doses higher than 10 ng/kg/min significantly decreased cardiac output, glomerular filtration rate, renal plasma flow, urine volume, and urinary sodium excretion. Mean arterial pressure showed a transient decrease at doses higher than 50 ng/kg/min. These results showed that endothelin in systemic administration has effects on renal functions as well as on systemic hemodynamics.

Anesthesia↗
PubMed1989

Effects of endothelin on renal regional blood flow in dogs.

The effects of intrarenal infusion of endothelin on renal blood flow were investigated in anesthetized dogs. Endothelin produced a biphasic change in the renal blood flow (RBF): an initial, transient increase followed by a marked, long-lasting decrease. The changes in the RBF were parallel to those in the renal cortical blood flow, whereas the changes in the medullary blood flow were less prominent. These results suggest that endothelin affects RBF, preferentially in the renal cortex.

Anesthesia↗
PubMed1989

Natriuretic and diuretic effects of endothelin in isolated perfused rat kidney.

In an attempt to clarify the pathophysiological role of endothelin (ET), a novel vasoconstrictor peptide, we administered this peptide into the medium of isolated perfused rat kidney (IPK). ET increased renal vascular resistance by 53%, and reduced inulin clearance by 29% in IPK at a higher concentration of 500 PM. However, fractional excretion of sodium and urine flow rate were increased by 160% and 109%, respectively. These findings suggest that ET modulates the tubular sodium reabsorption as well as the renal hemodynamics.

Animals↗
PubMed1989

Effects of atrial natriuretic peptide on regional renal blood flow measured by a thermal diffusion technique.

The effects of atrial natriuretic peptide (ANP) on the regional renal blood flow were examined in anesthetized dogs. A thermal diffusion technique was applied in an attempt to observe the intrarenal blood distribution. Tissue blood flow was continuously measured according to the changes of the thermal gradient produced by a semiconductor (Peltier effect). The data (x) obtained by these probes were closely related to those (y) of the ion gas clearance method (the probe for cortical blood flow; y = 1.08x-6.23 r = 0.99, the probe for medullary blood flow; y = 1.00x +0.26 r = 0.99). The basal values of cortical and medullary blood flows measured with the flow probe in anesthetized mongrel dogs were 85 +/- 16 and 55 +/- 9 ml/min/100 g kidney weight, respectively. ANP was infused into renal artery at doses of 0.01 (n = 6), 0.05 (n = 8), 0.3 (n = 6) micrograms/kg/min and the effect on renal hemodynamics and renal excretory functions was observed. The effect was also compared with that of furosemide. Low dose of ANP did not affect renal blood distribution. Intermediate dose of ANP selectively increased medullary blood flow from 46 +/- 8 to 62 +/- 7 ml/min/100 g kidney weight, and higher dose significantly increased both cortical and medullary blood flow. ANP produced diuresis and natriuresis in a dose-dependent manner, which was not necessarily related to the changes of intrarenal blood distribution. Furosemide did not affect the renal hemodynamics. Several parameters of renal functions such as lithium and free water clearances, showed changes different from those with ANP infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Renal and hemodynamic effects of synthetic atrial natriuretic peptide in dogs with chronic renal failure.

The present experiments were performed to clarify the renal and hemodynamic effects of atrial natriuretic peptide (ANP) in dogs with chronic renal failure (CRF; produced by 5/6 nephrectomy 3-4 weeks before study). Synthetic alpha-hANP was administered intravenously (0.1 micrograms/kg body weight for 30 min) with a priming bolus injection (1.0 micrograms/kg body weight) to anesthetized controls (n = 8) and CRF-dogs (n = 10). The effects of ANP on renal function, cardiac function, lithium clearance, and plasma ANP levels during clearance studies were determined. Effects of ANP on the hemodynamics were observed to the same degree in both groups. An increase in inulin clearance (CIn) was noted only in the CRF-dogs (7.5 +/- 2.1 to 9.6 +/- 2.9 ml/min; p less than 0.01). The infusion of ANP increased the urine volume, absolute sodium excretion, and osmolar clearance in the control and CRF groups. The fractional excretion of lithium (FELi), a marker of the proximal reabsorption of sodium, was higher at baseline in the CRF group (control group, 24.4 +/- 6.7 vs. CRF group, 41.5 +/- 13.2%; p less than 0.001). Following ANP infusion, FELi increased in both groups. The plasma ANP levels were monitored during the clearance study, and those of the CRF group were higher throughout the experiments. Thus, extrinsic ANP induced diuresis and natriuresis in CRF-dogs, produced by nephron mass reduction. Discrepancies in the pattern of response and plasma ANP levels were observed between the controls and CRF-dogs, suggesting that the action and metabolic clearance rate of ANP were altered in the CRF state.

Animals↗
PubMed1989

Role of atrial natriuretic peptide on sodium homeostasis in experimental renal failure.

In a study of the role of atrial natriuretic peptide (ANP) in sodium homeostasis in experimental renal failure, we found that a infusion of ANP at 0.25 microgram/min for 15 min produced an increase in the glomerular filtration rate (GFR) and fractional excretion of sodium (FENa) in five-sixth nephrectomized (5/6 Nx) rats. Renal vascular resistance (RVR) was lower during the base-line period and did not change after the administration of 100 ng/ml ANP to isolated perfused kidney (IPK) from adriamycin-treated rats. Furthermore, fractional excretion of ANP (FEANP) by IPK decreased in kidneys from adriamycin-treated rats as compared to that in kidneys from control rats. Finally, after 5/6 Nx, levels of plasma immunoreactive ANP (ir-ANP) gradually increased but excretion of water and sodium did not change during normal intake of sodium. The increase in levels of ir-ANP was accompanied by an increase in the rates of excretion of water and sodium was observed 2 days later but these rates returned to the base-line values after 2 weeks. These findings suggest that ANP plays an important role in the adjustment of acute changes in the volume of extracellular fluid during experimental renal failure.

Animals↗
PubMed1989

The effects of ciclosporin on the renal histopathological aspects in (NZB x NZW)F1 mice.

Ciclosporin A (CYA) is a newly developed immunosuppressant and has a sparing effect on suppressor cell regulatory mechanism. However, accumulation of experimental animal studies has not been enough for the administration of CYA to human autoimmune diseases such as lupus nephritis. In this study, the histopathological aspects of the kidney in (NZB x NZW)F1 mice after administration of CYA were analysed. A dose of 25 mg/kg/day of CYA was injected intraperitoneally so that serum level of CYA was controlled from 250 to 300 ng/ml with this dosage. Typical histopathological changes of lupus nephritis including wire-loop lesions were observed in the kidney of the non-treated control group. In contrast, only few lesions were demonstrated in the CYA-treated group. These results suggest that CYA prevented the renal deterioration in lupus mice.

Analysis of Variance↗
PubMed1989

Microscopic observation of leukocyte kinesis in the vascular bed during hemodialysis using the rabbit ear chamber technique.

Leukocyte kinesis in the capillary vascular bed during hemodialysis (HD) was investigated to elucidate the mechanism of transient leukopenia. Leukocyte movement was observed microscopically during HD using the rabbit ear chamber (REC) technique, which permits visualization of the movement of blood corpuscles in capillaries. Blood was drawn from the femoral artery and returned into the auricular and/or carotid artery so that the blood passing through the hollow fiber artificial kidney (HFAK) flowed into capillaries in the REC. Leukocyte counts of blood samples taken from the afferent and efferent limbs of the HD circuit, the right jugular vein and the right atrium were determined consecutively during HD. The difference in the leukocyte count was observed between the afferent and efferent limbs for the first 15 minutes and thereafter between the efferent limb and the jugular vein. The "transpulmonary" difference in the leukocyte count was not noticed throughout HD. Between 15 and 90 minutes after the start of HD, scarcely any circulating leukocytes were found in capillaries in the REC and some leukocytes were attached to the endothelial surface. Thereafter circulating leukocytes were seen again and detachment of leukocytes from the endothelial surface was observed. No leukocyte aggregation or embolization of aggregating leukocytes was noticed. This evidence suggests that leukopenia may be attributed to the transient shift of leukocytes to the marginal pool of the vessel lumen and this process may not be specific for the pulmonary vasculature, but may occur in the first capillary bed into which the blood passing through the HFAK flows.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Therapeutic effects of oral sorbent in undialyzed uremia.

The present study was carried out to clarify whether an oral sorbent, AST-120 (Kureha Chemical Ind Co, Tokyo), may postpone the initiation of dialysis therapy. The subjects were randomly divided into two groups, control and AST. The AST group consisted of 27 undialyzed uremic patients. Serum creatine concentrations (SCr) were 4.3 to 8.1 mg/dL (5.8 +/- 1.1 mg/dL, mean +/- SD). The control group consisted of 24 uremic patients who were not given AST-120 during the conservative therapy period before the initiation of hemodialysis. AST-120 (3.2 to 7.2 g/d) was administered to the patients in the AST group for 2.4 to 30.1 months (13.2 +/- 7.4) before the initiation of hemodialysis. The slopes of reciprocal creatinine v time in the control group were -1,251 +/- 856 x 10(-5) dL/mg/month during the 6 to 12 months before the initiation of dialysis therapy, and in the AST group, they were -1,004 +/- 1,012 x 10(-5) dL/mg/month before administration, and -347 +/- 509 x 10(-5) dL/mg/month after administration of AST-120 (P less than 0.01). All 24 patients in the control group and 21 of 27 in the AST group were introduced to hemodialysis. SCr and serum urea nitrogen (SUN) at the initiation of hemodialysis did not differ between the control and AST group: 10.8 +/- 2.6 and 11.0 +/- 2.2 mg/dL and 92.7 +/- 22.2 and 94.1 +/- 21.6 mg/dL, respectively. The times to the 50% undialyzed level were 5.0 months in the control group, and 14.3 months in the AST group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1988

Immunohistochemical localization of atrial natriuretic peptide binding sites in juxtaglomerular cells and vascular walls of rat kidney.

Since the kidney is one of the major sites of action for atrial natriuretic peptide (ANP) and immunoreactive ANP has been detected in tissue extract by radioimmunoassay, we have applied the immunohistochemical technique by using the avidin-biotin complex method to investigate ANP binding sites in the rat kidney. Although no immunostaining was observed in the kidney of control rats, immunoreactive ANP was present in the juxtaglomerular cells, the vascular walls of interlobular arteries, arcuate arteries, arterioles including vas afferens and vas efferens, and the medullary peritubular capillary of ANP-pretreated rats. In contrast, no tubular structure was stained. These results suggest that ANP may affect renin secretion via its direct action on the juxtaglomerular cells and that it predominantly induces natriuresis by its effects on renal hemodynamics.

Animals↗