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Biomedical subjects

F Marumo

Publications and source records attributed to F Marumo.

At least 613 records · Page 34Linked to original sources
PubMed1989

Plasma concentrations of atrial natriuretic peptide in children with persistent hypertension.

Plasma concentrations of human atrial natriuretic peptide (hANP) were determined in children with persistent hypertension and in age-matched normotensive controls. We studied 40 children 6-7 years of age (Group A), and 74 children 13-14 years of age (Group B). There was no significant difference in plasma hANP concentration between hypertensives and normotensives in group A. In group B, the plasma hANP concentration in hypertensives (86.5 +/- 44.9 pg/ml: mean +/- SD) was significantly higher than in normotensives (58.8 +/- 40.4 pg/ml) (p less than 0.01). In group B, 24-hour urinary excretion of sodium and fractional excretion of sodium were not significantly different between hypertensives and normotensives. The plasma hANP correlated significantly with the fractional excretion of sodium (p less than 0.05) and the 24-hour urinary excretion of sodium (p less than 0.01) in normotensives. No such correlation was evident in the case of the hypertensives. The pathogenesis of increased plasma hANP concentration in older children with persistent hypertension remains to be investigated. In regard to the effects of hANP on renal function, hANP may contribute to the regulation of sodium handling in normotensive adolescents, whereas other regulatory mechanisms need to be considered in the case of hypertensives.

Adolescent↗
PubMed1989

Leukotriene D4 inhibits atrial natriuretic factor-dependent cGMP production in rat glomerulus.

The effects of leukotriene D4 (LTD4) on guanosine 3',5'-cyclic monophosphate (cGMP) production induced by atrial natriuretic factor (ANF) or sodium nitroprusside (SNP) were investigated in isolated rat glomeruli. First, the isolated glomeruli were preincubated in Krebs-Ringer buffer containing 3-isobutyl-1-methylxanthine for 10 min, then incubated with varying concentrations of ANF, SNP, and LTD4 for 3 min. cGMP content was determined by radioimmunoassay. cGMP production (fmol.glomerulus-1.3 min-1) was not increased by LTD4. cGMP accumulation was increased by ANF (1 microM) and SNP (100 microM) remarkably from 0.19 +/- 0.09 to 3.24 +/- 0.21 (n = 7, mean +/- SE), and from 0.19 +/- 0.09 to 3.67 +/- 0.47 (n = 4), respectively. The increase in cGMP production by ANF was significantly and dose-dependently inhibited by LTD4 (P less than 0.05). Maximum suppression was observed at the concentration of 100 nM (from 3.06 +/- 0.33 to 1.43 +/- 0.09; P less than 0.05). However, LTD4 caused no significant change in the level of cGMP production induced by SNP. Second, particulate or soluble guanylate cyclase from glomeruli were similarly investigated. ANF selectively activated particulate guanylate cyclase and the response was selectively inhibited by LTD4 from 9.07 +/- 1.79 fmol.micrograms-1.3 min-1 (n = 6) to 4.70 +/- 0.70 (n = 6, P less than 0.05). These results suggest the site where LTD4 has effect on cGMP production induced by ANF was the particulate guanylate cyclase system, but not the soluble guanylate cyclase system.

1-Methyl-3-isobutylxanthine↗
PubMed1989

Effects of carbonic anhydrase inhibitors on basolateral base transport of rabbit proximal straight tubule.

The effect of carbonic anhydrase inhibitors on basolateral base transport was examined in rabbit proximal straight tubules (S2 segment) perfused in vitro by double-barreled pH microelectrodes. Bath HCO3- reduction or Na+ removal induced an initial basolateral voltage (Vbl) depolarization followed by a late-phase depolarization. Administration of 1 mM acetazolamide (ACTZ) to the bath fluid caused a small inhibition of the initial depolarization, and a larger inhibition of the late phase depolarization. Bath HCO3- reduction decreased intracellular pH (pHi), and this pHi decrease was attenuated by ACTZ. Bath Na+ removal also decreased pHi, and this pHi decrease was completely blocked by ACTZ. However, a slow pHi decrease was observed in response to bath Na+ removal when the bath fluid contained ACTZ and the luminal fluid contained 4 mM amiloride. The addition of ACTZ or ethoxyzolamide to the bath caused a rapid Vbl hyperpolarization and pHi increase. These results demonstrate that carbonic anhydrase inhibitors inhibit basolateral Na(HCO3)n transport in intact rabbit proximal tubule cells (S2). The data suggest that at least one of the base species transported by the transporter is HCO3-, and cytosolic carbonic anhydrase is important in converting intracellular OH- to HCO3-.

Acetazolamide↗
PubMed1989

Severity and pathophysiology of heart failure on the basis of anaerobic threshold (AT) and related parameters.

Cardio-pulmonary exercise testing was performed in 99 normal subjects and 382 patients with cardiac disease in order to evaluate anaerobic threshold (AT) and related parameters as indices for assessing the severity of heart failure. AT could be determined easily during ergometer exercise testing with ramp protocol by monitoring minute ventilation (VE), oxygen uptake (VO2) and carbon dioxide output (VCO2). Peak VO2 and the ratio of VO2 rising to work rate increment (delta VO2/delta WR) were also determined. There was good correlation between the AT determined by respiratory measurement and that determined by arterial lactic acid concentration (r = 0.93, n = 15). The reproducibility of AT was excellent between 2 testings with a 3-hour interval. AT (ml/min/kg) and peak VO2 (ml/min/kg) declined with age, and males showed higher values than females in both indices. %AT, determined by the predicted AT values of each age and sex, decreased as NYHA class progressed as follows: 90.2 +/- 15.4% in class I, 76.9 +/- 13.8% in class II, and 59.7 +/- 11.9% in class III. Although delta VO2/delta WR was not influenced by age or sex, it also decreased as the severity of heart disease progressed. These results suggest that indices from cardiopulmonary exercise testing, especially AT, are closely related to the pathophysiology of heart failure, so that they are objective and reliable parameters for evaluation of the severity of heart failure and are sensitive enough to detect the efficacy of therapeutic intervention for heart failure.

Adolescent↗
PubMed1989

Clinical significance of renal hemodynamics in severe congestive heart failure: responsiveness to ultrafiltration therapies.

Isolated ultrafiltration, hemodialysis & peritoneal dialysis (Tx) were recently used in the treatment of intractable heart failure (HF). We examined the relation between the response of HF to Tx and the residual kidney functions. Tx was carried out in 17 patients (Pts) with HF who did not respond to aggressive medical treatment. Ten Pts (R) responded to Tx and 7 Pts (N) did not. Serum urea nitrogen (UN), creatinine (Cr), uric acid (UA), sodium (Na), potassium (K), and chloride (Cl) concentrations on admission and before Tx were not different between R and N. Urine UN, Cr, Na, K, and Cl on admission and before Tx were also not significantly different. Fractional sodium excretions (FENa), renal failure indices (RFI), and urine/plasma Cr ratios (U/P Cr) on admission were 2.0 +/- 1.6, 2.7 +/- 2.2, and 30.5 +/- 20.0 in R and 5.9 +/- 4.2, 8.2 +/- 6.0 and 11.5 +/- 3.8 in N. They were significantly different (p less than 0.05). However, these did not differ before and after Tx. These data show that FENa, RFI and U/P Cr might be useful indices in predicting the responsiveness of intractable HF to Tx.

Adult↗
PubMed1989

No specific organ removes atrial natriuretic peptide from the human plasma.

The fate of atrial natriuretic peptide (ANP) was studied by arterial and venous catheterization in ischemic heart disease patients, and arterio-venous blood sampling in healthy kidney donors at the time of transplantation. In vitro ANP degradation was examined using healthy human plasma. In ischemic heart disease, the plasma ANP concentration at the inferior vena cava was 62.6% of that at the left ventricle, and that at the superior vena cava was 82.8%. Arterio-venous gradients were similar from pulmonary artery to vein (88.3%), from celiac artery to the hepatic vein (75.5%) and from the femoral artery to vein (85.4%). In the donor for kidney transplantation, renal arterio-venous gradient was also similar at 77.1%. No platelet consumption of ANP was noted, and the molecular forms of ANP present in the circulation were similar in samples obtained from both the coronary sinus and the superior or inferior vena cava. We conclude that no specific organ plays a dominant role in ANP degradation, and that ANP molecular forms may not be altered during circulation.

Adolescent↗
PubMed1989

Extracorporeal circulation influence on plasma atrial natriuretic peptide concentration in cardiac surgery patients.

An attempt was made to clarify the change of plasma human atrial natriuretic peptide (hANP) concentration before, during, and after cardiac surgery in heart failure with extracorporeal circulation. Plasma hANP concentration did not significantly decrease during total aortic cross clamping (ACC) with complete clamping of the superior and inferior vena cavae. This finding may be explained by the suppression of endopeptidase activities and the response of hANP receptors due to the low body temperature. Plasma hANP concentration strongly increased from 56.6 +/- 8.4 to 208.9 +/- 40.7 pg/ml (n = 5) by the release of total ACC. This strong increase of hANP in the plasma may occur due to the rapid increase of atrial pressure from zero to 12.5 mm Hg caused by releasing the total ACC. The molecular form of plasma hANP obtained after the release of total ACC was alpha-hANP alone, which was estimated by gel permeation chromatography and reverse HPLC.

Adult↗
PubMed1989

Degradation of atrial natriuretic peptide in dogs.

To clarify the degradation of atrial natriuretic peptide (ANP) in dogs, plasma ANP concentrations in blood samples drawn from the coronary sinus, and in simultaneously collected blood samples of the arteries and veins of the lung, liver, kidney, spleen and cervix, and of the supramesenteric artery and the portal vein, were measured, both when infused with exogenous ANP (280 ng.kg-1.min-1, N = 7) and when not infused (N = 6). Venous ANP concentrations in most organs showed lower values than arterial levels by 11.6 to 33.6%, suggesting degradation during circulation. Exogenous ANP infusion resulted in a 26.0 to 41.9% arterio-venous decrease in ANP levels. These findings suggest that each organ contributes to ANP degradation, and that no specific organ plays a key role. The plasma ANP concentration was not reduced when blood samples were incubated for 60 min at 37 degrees C. The plasma from the coronary sinus and forearm vein contained essentially identical ANP molecular forms, as shown by gel permeation chromatography. Thus, the blood circulation through various organs does not cause high molecular weight ANP to be changed to other forms.

Animals↗
PubMed1989

[Effects of hemodialysis on left ventricular performance: a Doppler echocardiographic study].

Left ventricular systolic and diastolic performance was examined using Doppler and M-mode echocardiography in 42 patients with chronic renal failure before and after hemodialysis. Twenty patients with left ventricular hypertrophy, 22 without hypertrophy and 30 normal subjects were studied. Chronic renal failure patients showed significantly larger chamber diameters of the left ventricle, left atrium and right ventricle than did normal subjects. This group also exhibited greater fractional shortening, stroke volume and cardiac output. Before hemodialysis, patients with left ventricular hypertrophy had a significantly higher cardiac output and the greater ratio of late to early diastolic peak flow velocities (A/R) than did patients without hypertrophy. After hemodialysis, there were significant reductions in blood pressure, ventricular and atrial dimensions, stroke volume and cardiac output. The velocities of early and late diastolic left ventricular filling and the deceleration rate were also significantly reduced. The heart rate, A/R, deceleration half time, and the ratio of deceleration half time to acceleration half time (DHT/AHT) were significantly increased. The greater the amount of fluid removed, the greater the changes in the above values. Patients with left ventricular hypertrophy exhibited significant reductions in fractional shortening, ejection fraction, stroke volume and cardiac output, compared to those without hypertrophy. However, patients without hypertrophy showed more significant decrease in the acceleration half time and increase in DHT/AHT than did patients with hypertrophy. These findings demonstrated normal systolic function and impaired diastolic properties in patients with chronic renal failure, who had left ventricular hypertrophy unaccompanied by dilatation.

Adult↗
PubMed1989

[Effect of recombinant human erythropoietin administration on cardiovascular system in patient with chronic renal failure: an analysis of the blood pressure upward].

To investigate the mechanism of blood pressure upward after recombinant human erythropoietin (EPO) administration in patient with chronic renal failure (CRF), hemodynamic changes following on the improvement of anemia was evaluated by the echocardiography. Fourteen (5 males, 9 females) normotensive patients with less than 23% of hematocrit (HT) were administered 1,500 approximately 3,000 units of EPO three times a week. Four patients with systolic (greater than 160 mmHg) or diastolic (greater than 90 mmHg) hypertension after EPO administration was named group H, the remaining patients was named group N. Blood pressure, heart rates and parameters of echocardiography examined after the improvement of anemia were compared to those examined before EPO administration, respectively. Patients had an increase in Ht from 20.0 +/- 1.6% to 33.0 +/- 1.9% (p less than 0.01). LVDd, LVEDV, CO and flow velocity in group N were significantly decreased after EPO administration; while those in group H did not show the significant changes. IVSth and LVPWth in each group were significantly increased after EPO administration. These data showes that decrease in CO maintains the patients normotensive after EPO administration.

Adult↗
PubMed1989

Improved determination of vanadium in biological fluids by electrothermal atomic absorption spectrometry.

We made sensitive and accurate electrothermal atomic absorption spectrometric measurements of vanadium in small volumes of serum. The wet-digested sample was extracted into an organic solvent, with N-benzoyl-N-(o-tolyl)hydroxylamine (BTA) as the chelating reagent. After evaporating the solvent, we dissolved the residue in acetic acid, and injected a 60-microL aliquot into a graphite furnace. In this way we could measure vanadium concentrations as low as 80 ng/L in 4 mL of serum. The within-run CV was 3.3% for serum, 7.7% for urine. Analytical recoveries of vanadium added to serum and urine were 90.3% and 90.8%, respectively. We measured vanadium concentrations in sera from 64 healthy persons (group 1), 15 nondialyzed uremic patients (group 2), and 11 hemodialyzed patients (group 3). The highest concentration of vanadium in group 1 was 240 ng/L; about 60% of the values for this group were less than 80 ng/L. In group 3, the vanadium concentrations were extremely high (15 +/- 14.2 micrograms/L, mean +/- SD), less so (but still above normal) in group 2 (1.58 +/- 3.16 micrograms/L).

Adult↗
PubMed1988

ATP-driven Ca2+ pump in the basolateral membrane of rat kidney cortex catalyzes an electroneutral Ca2+/H+ antiport.

An ATP-driven Ca2+ pump in the basolateral membrane of rat kidney cortex pumps Ca2+ out of the cell at the expense of MgATP (Km = 0.191 mM). This pump has a high affinity for free Ca2+ (26 nM). Vanadate, lanthanum, N-ethylmaleimide and calmodulin inhibitor R24571 inhibited this pump activity. Dimethyl[2-14C]oxazolidine-2,4-dione [( 14C]DMO) was entrapped in the vesicles in association with the ATP-driven Ca2+ influx. The ATP-driven Ca2+ influx was stimulated by the intravesicular acid pH and an upper convex Lineweaver-Burk reciprocal plot suggested two possible kinetics; one is that this Ca2+ pump is an allosteric enzyme with more than 1.72 H+ binding sites and another is the presence of two Ca2+ pumps with different affinities for H+. Valinomycin study indicated that the ATP-dependent Ca2+ transport by the BLMV was electroneutral and voltage independent. These results strongly suggest that the ATP-driven Ca2+ pump in the renal basolateral membrane catalyzes an electroneutral Ca2+/H+ antiport.

Adenosine Triphosphate↗
PubMed1988

Brain natriuretic peptide interacts with atrial natriuretic peptide receptor in cultured rat vascular smooth muscle cells.

The effect of synthetic porcine brain natriuretic peptide (pBNP), a novel brain peptide with sequence homology to alpha-human atrial natriuretic peptide (hANP), on receptor binding and cGMP generation, was studied in cultured rat vascular smooth muscle cells (VSMC) and compared with that of alpha-hANP. 125I-pBNP bound to the cells in a time-dependent manner similar to that of 125I-alpha-hANP. Scatchard analysis indicated a single class of binding sites for pBNP with affinity and capacity identical to those of alpha-hANP. pBNP and alpha-hANP were almost equipotent in inhibiting the binding of either radioligand and stimulating intracellular cGMP generation. These data indicate that BNP and ANP interact with the same receptor sites to activate guanylate cyclase in rat VSMC.

Animals↗