Ion channels in the luminal membrane of endothelial cells of the bull-frog heart

Ion channels in the luminal membrane of intact endothelial cells of the bull-frog atrium were examined with single channel recordings. A class of outwardly rectifying channels and at least two types of ohmic channels were recorded without any stimulation by vasoactive substances. The slope conductances of the outwardly rectifying channel measured at potentials positive to and negative to the reversal potential were 36.4 +/- 8.8 and 7.5 +/- 2.2 pS, respectively (n = 35). This channel was a cation channel with poor selectivity between K+ and Na+ (PNa/PK = 1.04 +/- 0.08, n = 3). The open probability and mean open time increased as the membrane was depolarized. The two ohmic channels had single channel conductances of 175.3 +/- 17.7 (n = 21) and 9.5 +/- 1.8 pS (n = 11), respectively. The 175pS channel also failed to discriminate between K+ and Na+. Its open probability was voltage-independent. Internal Ca2+ affected none of the channels examined. The luminal membrane may have a population of ion channels different from the abluminal membrane. These characteristics were different from those so far described in the cultured endothelial cells from mammalian blood vessels.

[Determination and clinical significance of human hepatocyte growth factor in serum]

Hepatocyte growth factor (HGF) is the most potent mitogen for mature parenchymal hepatocytes in primary culture, and seems to be a hepatotrophic factor that acts as a trigger for liver regeneration after partial hepatectomy and liver injury. In the present study, we evaluated an enzyme-linked immunosorbent assay, using monoclonal antihuman HGF (h-HGF) antibody, for measuring serum h-HGF levels. Intra- and inter-assay coefficients of variation were 2.2-3.3% and 3.4-4.0%, respectively. Detection limit of this method was 0.1 ng/ml, determining by the dilution test. The substances tested did not interfere with this assay, except for high concentrations of hemoglobin. Furthermore, no interference was observed with plasminogen and lipoprotein (a), which show the structural homology to h-HGF, and with various kinds of cytokines. Reference ranges of serum h-HGF determined with 187 healthy subjects were 0.1-0.23 ng/ml. Serum h-HGF concentrations were increased in various kinds of liver diseases, in particular those were significantly higher in fulminant hepatic failure. Furthermore, prognosis of the patients with higher h-HGF values were strikingly worse than those with lower levels. We concluded that the determination of serum h-HGF plays important roles in the early diagnosis and prognosis of fulminant hepatic failure.

[Flow cytometric determination of active oxygen produced by neutrophils in patients with inflammatory diseases]

We investigated active oxygen (H2O2) production by neutrophils in patients with inflammatory diseases such as connective tissue disease and respiratory tract infection. The analysis was done by flow cytometry using as small volume of whole-blood as 100 microliters. H2O2 production as well as C-reactive protein (CRP) were increased in connective tissue diseases, and was decreased after steroid therapy. In a case of neuro-Behçet's disease, changes in H2O2 production was observed in agreement with those in clinical symptoms such as gait disturbance. H2O2 production as well as CRP and neutrophil count were increased in acute respiratory tract infection, but in chronic patients H2O2 production alone was rather reduced. In stages of enhanced H2O2 production, tissue damage or inflammation may exist, the degree of which seems to be well reflected by H2O2 production. During stages of impaired H2O2 production, care should be taken to prevent infections. Using flow cytometry, H2O2 production can be easily determined as one of functions of neutrophils.

Increased serum apoA-IV concentrations in experimental uremic rats

Normal histochemical analysis localizes apoA-IV within renal proximal tubules, which suggests that the kidney is a major catabolic site. In clinical renal failure and animal models of decreased renal function, low molecular weight proteins cannot be efficiently filtered through the glomerular basement membrane, and therefore they accumulate in plasma. In normal plasma, apoA-IV exists as both lipoprotein associated and lipoprotein-free, low molecular weight forms. To examine this further, uremic serum apolipoprotein and mRNA levels were examined in surgically 5/6 nephrectomized rats. Compared to sham-operated controls, uremic serum apoA-IV was elevated twofold and was distributed to a greater extent in the lipoprotein-free subfraction. Serum triglycerides were unchanged. Despite finding no correlation between serum apoA-IV and triglyceride levels (in either the d less than 1.006 g/ml or 1.006 less than d less than 1.019 g/ml fraction), serum apoA-IV was positively correlated with the renal function parameters of blood urea nitrogen (r = 0.949, P less than 0.001), creatinine (r = 0.952, P less than 0.001), and uric acid (r = 0.903, P less than 0.001). In addition, the concentration of apoA-IV per milligram of renal homogenate protein in uremic rats was significantly higher than that of control rats, whereas there was no difference in the content of apoA-I between the two groups. ApoA-I, apoA-IV, and apoB mRNA levels in hepatic and in intestinal tissue were undistinguishable between the uremic and surgical sham rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on apolipoprotein(a) phenotypes. Part 1. Phenotype frequencies in a healthy Japanese population

The frequency distribution for serum lipoprotein(a) (Lp(a)) concentrations in healthy Japanese was highly skewed, with a mean +/- S.D. of 14.6 +/- 13.6 mg/dl and a median of 11.0 mg/dl. The present study provides the first evidence on the frequencies of Lp(a) phenotypes and alleles in healthy Japanese subjects. There was a strong inverse relationship between the apparent molecular weights of apo(a) isoforms and plasma Lp(a) concentrations, as reported previously. However, because of the considerable overlap between the Lp(a) concentrations of the different phenotypes, it was impossible to predict Lp(a) concentration from Lp(a) phenotypes, or vice versa. The present results suggest that the distribution of Lp(a) concentrations, mean and median values and Lp(a) phenotype and allele frequencies in healthy Japanese are not significantly different from the results for Europeans, whereas they are significantly different from other Asian populations, i.e. Chinese, Indians and Malaysians.

Studies on apolipoprotein(a) phenotypes. Part 2. Phenotype frequencies and Lp(a) concentrations in different phenotypes in patients with angiographically defined coronary artery diseases

In the present paper, we have evaluated serum Lp(a) concentrations, the frequencies of Lp(a) phenotypes and alleles and the association between the Lp(a) phenotypes and serum Lp(a) levels in 470 patients with angiographically defined coronary artery disease (CAD). Serum Lp(a) concentrations were significantly increased in proportion to the number of diseased vessels in the CAD patients. The frequencies of Lp(a) phenotypes in the CAD patients were significantly different from those in healthy subjects. In particular, the frequency of double-band phenotypes was higher in the CAD group. The frequencies of Lp(a) alleles in the CAD patients, however, were not significantly different from those in the healthy subjects. There was a strong inverse relationship between the apparent molecular weights of apo(a) isoforms and serum Lp(a) concentrations. Lp(a) levels in the CAD patients were higher than those in the healthy subjects with the same phenotype. The present results suggest that it is important to consider some posttranslational or environmental modifications and other factors, in addition to the genetic factor, when assessing contributions to plasma Lp(a) levels.

[Changes in serum cytokine levels in patients with malignant bone and soft tissue tumors in the course of chemotherapy]

We studied seven patients with malignant bone and soft tissue tumors to examine the influence of chemotherapy on production of serum cytokines. Four types of cytokines (IL-1 beta, IL-2, IL-6, TNF alpha) were measured by ELISA method. A significant increase of IL-6 and TNF alpha production was observed after intravenous infusion of antitumor drugs. After intraarterial infusion of drugs there was a slight increase in the production of these cytokines. On the other hand, there were no changes in the IL-1 beta and IL-2 levels after infusion of the drugs. IL-6 and TNF alpha increased almost at the same time that the numbers of WBC (neutrophils) decreased after infusion. And this phenomenon was clear in the patients who had a good performance status.

Sensitive, direct procedures for simultaneous determinations of iron and copper in serum, with use of 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (nitro-PAPS) as ligand

We developed a direct, simple, and sensitive procedure for the simultaneous colorimetric assay of iron and copper in serum, using sodium dodecyl sulfate-ascorbic acid to dissociate iron and copper from transferrin and ceruloplasmin, respectively. We also use a new water-soluble reagent, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol disodium salt (nitro-PAPS) and thioglycolic acid to eliminate interference from copper in the measurement of iron. Within- and between-run precisions of the present method were 2.5-2.8% for iron and 1.8-4.6% for copper. The proposed method is susceptible to interference by hemoglobin and lipemia, especially for the iron assay. Linear-regression analyses of results of the proposed method with those of the bathophenanthroline method for iron and of the atomic absorption spectroscopic method for copper correlated well (r = 0.996, Sy/x = 0.73 and r = 0.959, Sy/x = 1.11, respectively).

Common variable immunodeficiency with increased surface IgM-positive double-bearing B cells

We report a case of common variable immunodeficiency (CVI) that shows low levels of IgG and IgA, but a normal quantitative or qualitative level of IgM. T-cell functions were not disturbed. Increased numbers of surface IgM (sIgM) and sIgD, sIgM and sIgG, sIgM and sIgA double-bearing B cells were observed as compared with a control. No IgG and IgA induction upon stimulation with Staphylococcus aureus Cowan I (SAC) and recombinant interleukin-2 (rIL-2), or pokeweed mitogen (PWM) and rIL-4 or rIL-6 was observed, although there was proliferation. Although mu mRNA was expressed as much as in a healthy control, transcription of gamma mRNA and alpha mRNA was very low. Furthermore, no enhanced effects of gamma mRNA and alpha mRNA were recognized upon stimulation with rIL-4 and rIL-6. These results suggest that the patient's B cells might be defective at the switching process from mu, mu and delta, mu and gamma to gamma or mu and alpha to alpha.

Sensitive, Direct Procedures for Simultaneous Determinations of Iron and Copper in Serum, with Use of 2-(5-Nitro-2-Pyridylazo)-5-(N-Propyl-N-Sulfopropylamino)Phenol (Nitro-PAPS) as Ligand

We developed a direct, simple, and sensitive procedure for the simultaneous colorimetric assay of iron and copper in serum, using sodium dodecyl sulfate-ascorbic acid to dissociate iron and copper from transferrin and ceruloplasmin, respectively. We also use a new water-soluble reagent, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol disodium salt (nitro-PAPS) and thioglycolic acid to eliminate interference from copper in the measurement of iron. Within- and between-run precisions of the present method were 2.5-2.8% for iron and 1.8-4.6% for copper. The proposed method is susceptible to interference by hemoglobin and lipemia, especially for the iron assay. Linear-regression analyses of results of the proposed method with those of the bathophenanthroline method for iron and of the atomic absorption spectroscopic method for copper correlated well (r = 0.996, Sy/x = 0.73 and r = 0.959, Sy/x = 1.11, respectively).

External K+ increases Na+ conductance of the hyperpolarization-activated current in rabbit cardiac pacemaker cells

The hyperpolarization-activated current (I(f)) was recorded from single myocytes dissociated from rabbit sinoatrial node. Although I(f) is usually carried by both Na+ and K+, removal of the minor K+ component from physiological saline suppresses inward component. This inward Na+ current through I(f) channel increases on raising the extracellular K+ concentration. The Na+ conductance relative to K+ conductance (PNa/PK), as measured from the reversal potential, increases and saturates near 5 mM K+. This effect is different from the current increase caused by raising the concentration of carrier ion K+, which saturates at 70 mM with a half-maximal value (K1/2) of 10 mM. It is suggested that the I(f) channel has multiple, interactive binding sites for cation permeation.

[Evaluation of cardiac functions in patients with progressive systemic sclerosis (PSS)]

Cardiac functions in 20 female patients with PSS were measured by ultrasound cardiography and compared with those of 10 healthy age-matched controls. The following results were obtained: 1) The patients with PSS showed the increases in left ventricular mass (LVmass), interventricular septal thickness (IVS) and left ventricular posterior wall thickness (LVPW) more than those of controls. 2) Diastolic descent rate (DDR) of patients decreased significantly in comparison with the healthy controls. 3) Right ventricular dimension (RVD) of patients were demonstrated to dilate more than those of controls. Conclusively ultrasound cardiography (UCG) is an available method for detecting the cardiac lesion of PSS. Abnormal signs were recognized even though their clinical features were limited to the extremities.

Blockade of the ATP-sensitive K+ channel by 5-hydroxydecanoate in guinea pig ventricular myocytes

Effects of a novel antiarrhythmic agent, 5-hydroxydecanoate (5-HD), were investigated on the electrical activity of the guinea pig ventricular myocytes. The shortening of action potential duration induced by applying iodoacetate (IAA) for 5 to 10 min was reversed completely by 5-HD (100 microM) in the papillary muscle. The single channel current recording in the cell-attached configuration revealed both activation of the ATP-sensitive K+ channel during the treatment with IAA and after depression of the channel by the additional application of 100 microM 5-HD. The quick rundown of the ATP-sensitive K+ channel activity interfered the analysis of the drug effect in the usual inside-out patch configuration. The channel activity in the isolated patch was partially recovered and stabilized by applying a tissue extract, which was prepared from guinea pig ventricle. Under this condition relationship between the 5-HD concentration and the K+ channel open probability was characterized with a K1/2 of 0.16 microM and a Hill coefficient of 0.88. The open- and close-time analysis revealed a decrease of the mean duration of the bursting channel opening and an increase of the interburst time under the effect of 5-HD. The inward-rectifier K+ channel, responsible for the resting K+ conductance, was not affected by 5-HD. It was concluded that the curative effect of 5-HD on the shortened action potential in the IAA-treated myocytes is mediated by the depression of the ATP-sensitive K+ channel.

Distribution of the isoprenaline-induced chloride current in rabbit heart

Current density of the isoprenaline-induced chloride current (ICl) was measured in sino-atrial (SA) node cells and atrial and ventricular myocytes dissected enzymatically from the rabbit heart. In addition to the conventional voltage clamp method the whole-cell patch clamp method using nystatin was employed to avoid run-down of ICl in dialysed cells. Isoprenaline (0.3 microM) failed to induce ICl in the 20 atrial cells examined. The integrity of the beta-adrenergic system was established by recording the response of the Ca2+ current in the same cell. Both isoprenaline and acetylcholine failed to affect the background membrane conductance in the 20 SA node cells studied. Myocytes isolated from the epicardial region of the left ventricular wall showed relatively higher ICl density (24.9 +/- 12.1 microS/microF) than those from the endocardial side (12.3 +/- 8.5 microS/microF). We conclude that beta-receptor-operated ICl is insignificant in atrial and SA node cells.

Control of the hyperpolarization-activated cation current by external anions in rabbit sino-atrial node cells

1. Effects of varying concentrations of anions on the hyperpolarization-activated current (I(f)) were studied in myocytes isolated from the rabbit sino-atrial node. Substituting Cs+ for the intracellular K+ clearly separated I(f) from the delayed rectifier K+ current. Control properties, including gating kinetics and ion selectivity, similar to previous studies were obtained. 2. Substitution of extracellular Cl- with larger anions including isethionate, glutamate, acetate, and aspartate, reduced the amplitude of I(f) without changing the reversal potential. Substitution with small anions such as iodide or nitrate supported an intact I(f). These effects were reproduced in the excised outside-out patch conformation. 3. The conductance for I(f) was a saturating function of the extracellular Cl- concentration ([Cl-]o) with an equilibrium binding constant (K1/2) of 11 mM and a slope factor of about 1 when substituted with large anions. Total removal of small anions completely abolished I(f). 4. The voltage-dependent gating of I(f) was not affected by changing ([Cl-]o), suggesting that Cl- modulates conductance properties of I(f). 5. The results indicate that I(f) conductance is unique in that it is dependent on an extracellular anion (Cl-), yet it is carried exclusively by cations, K+ and Na+. These effects are independent of any measurable voltage-dependent gating parameters.

Synergistic action of cyclic GMP on catecholamine-induced chloride current in guinea-pig ventricular cells

1. Effects of cyclic GMP on the catecholamine-induced chloride current (ICl) were studied using the whole-cell patch-clamp technique combined with internal perfusion in single ventricular myocytes dispersed from guinea-pig heart. 2. When ICl was activated by submaximal doses of isoprenaline (0.01-0.1 microM), adrenaline (0.5-1 microM) and histamine (0.2-0.5 microM), intracellular dialysis with cyclic GMP (10-100 microM) induced an extra increase of ICl. No further increase of ICl was induced by cyclic GMP when ICl was maximally activated. In the absence of agonists, cyclic GMP failed to induce ICl. 3. The enhancement by cyclic GMP was also observed when ICl was activated by external application of 0.2-1.0 microM-forskolin or by internal dialysis with a pipette solution containing 50-200 microM-cyclic AMP. 4. In contrast to cyclic GMP, 10-1000 microM-dibutyryl cyclic GMP and 8-bromo-cyclic GMP were ineffective in modifying ICl. 5. Milrinone (1-10 microM), a specific inhibitor of a kind of phosphodiesterase which is inhibited by cyclic GMP, also enhanced ICl activated by submaximal doses of isoprenaline. Milrinone itself did not activate ICl. 6. When ICl was enhanced by 5 microM-milrinone, an additional application of cyclic GMP failed to increase ICl. In the presence of cyclic GMP, milrinone failed to enhance ICl. 7. The above findings on ICl are analogous to the enhancement by cyclic GMP of the beta-adrenergic stimulation of the Ca2+ current reported in the same preparation, and support the hypothesis that in mammalian cardiac cells cyclic GMP potentiates elevation of cyclic AMP induced by beta-adrenergic agents, and thereby increases the amplitudes of ionic currents.

Exponential activation of the cardiac Na+ current in single guinea-pig ventricular cells

1. The cardiac Na+ current of guinea-pig was recorded using an improved oil-gap voltage clamp method. When a single ventricular cell was stretched between the internal and external solution compartments across an oil gap of about 40 microns in width, the sealing resistance in the oil gap was higher than 1 G omega and the time constant of the capacitive current was between 10 and 40 microseconds. Effective series resistance (Rs) was less than 50 k omega after Rs compensation. 2. The activation time course (I'Na) was separated from inactivation by dividing the digitized record of Na+ current with the inactivation variable h(t), which was obtained by fitting exponential functions to the decaying phase of current. I'Na started as a single exponential activation at time 0, which was defined by the decay of the capacitive current to 5% of its peak. 3. The Na+ tail current was recorded on repolarization after a short (1.2 ms) depolarizing pulse to -10 mV. Its single exponential decay at potentials negative to -50 mV, or its major exponential component of decay between -50 and -30 mV, was attributed to deactivation. The time constants of deactivation were similar to those of activation which were measured from I'Na on depolarization to comparable potentials. The m1 kinetics gave a better fit for Na+ activation than the m3 kinetics. 4. The time constant of deactivation was a linear function of the membrane potential on a semilogarithmic scale with an e-fold increase per 21.6 +/- 1.3 mV (n = 8) depolarization. The steady-state activation value (m(infinity)) was obtained from the amplitude of I'Na. Fitting a Boltzmann equation indicated a half-activation potential of -21.9 +/- 1.7 mV and a slope factor of 7.9 +/- 0.4 mV (n = 9). 5. m1 kinetics are more pertinent to a description of the cardiac Na+ current. Limitations in analysing the activation kinetics of Na+ current are discussed for the improved oil-gap voltage clamp method.

Effects of mechanical stretch on membrane currents of single ventricular myocytes of guinea-pig heart

A technique to record whole cell membrane current during stretching single cardiac myocytes was developed. Ventricular myocytes were dissociated by treating guinea-pig hearts with collagenase. One end of the cell was fixed either to a microglasstool tip or to a glass plate, while the other end was attached either to a microglasstool tip or to a suction pipette, which was mounted on a micromanipulator. A time-independent current showing a reversal potential of -15 +/- 4 mV (n = 7) was activated when the myocytes were stretched more than 20% of the length between two fixed point. The current gradually relaxed during the maintained stretch, and disappeared on releasing the stretch. We failed to detect any consistent change in either the L-type Ca2+ current or the inward rectifier K+ current. For comparison, current changes induced by inflating the cell using a hypo-osmotic solution were recorded. The inflation was not accompanied by any change in the time-independent current. Instead, the delayed rectifier K+ current was increased to 170 +/- 48% control by the 70% hypo-osmotic solution. Thus, the effect of mechanical stretch on the time-independent current is different from those of hypo-osmotic cell inflation. The stretch-induced time-independent current is compared with reported current changes induced by the intracellular microinjection of Ca2+.

[Serum lipid and apolipoprotein levels in patients with chronic pancreatitis]

Serum lipid and apolipoprotein (apo A-I, A-II, A-IV, B, C-II, C-III, E and H) levels were determined in 26 patients with chronic pancreatitis without complications such as liver disease or diabetes mellitus. These patients were divided into two groups, CP-I (n = 16) and CP-II (n = 10), according to the clinical criteria for chronic pancreatitis. HDL-cholesterol and apo A-I levels in CP-I and CP-II groups significantly decreased compared to those in sex- and age-matched healthy controls (p less than 0.05), whereas there were not significant differences in triglyceride and total cholesterol levels between these groups and controls. On the other hand, apo A-IV levels in CP-I and CP-II were 7.1 +/- 1.0 mg/dl and 8.3 +/- 1.5 mg/dl, respectively and these values were significantly lower than 11.2 +/- 1.8 mg/dl in controls (p less than 0.001). In this study, the serum lipids apparently showed normal levels in patients with chronic pancreatitis who had no severe complication, and the markedly low apo A-IV levels in these patients were considered to be mainly due to the decrease of lipid absorption from the intestine.

Cytosolic free Ca2+ during operation of sodium-calcium exchange in guinea-pig heart cells

1. Membrane current generated by the Na(+)-Ca2+ exchange mechanism was recorded in single guinea-pig ventricular myocytes using the whole-cell voltage-clamp technique and the intracellular free calcium concentration ([Ca2+]i) was monitored using the fluorescent probe Indo-1, applied intracellularly through a perfused patch pipette. The reversal potential of the exchanger (ENa, Ca) was measured from records of the 2 mM-Ni(2+)-sensitive current and used in an attempt to clamp [Ca2+]i at a level determined by the ionic compositions of the external and pipette solutions. 2. Measurements of ENa, Ca indicated that [Ca2+]i was close to that in the pipette solution when the holding potential was set at the ENa, Ca expected for a 3Na+:1Ca2+ exchanger. The measured value of ENa, Ca was more positive than the theoretical value when the membrane potential was held positive to ENa, Ca and the opposite was true when the holding potential was more negative than the expected ENa, Ca. 3. As Indo-1 diffused into the cell from the whole-cell clamp electrode, the intensities of the fluorescent signals measured at 405 and 480 nm increased with time, with no obvious saturation over a 10-45 min recording period. However, the ratio of these two signals reached a steady level within 5 min after rupture of the patch membrane, when the holding potential was set at the expected ENa, Ca of the exchanger. The intensity ratios measured using pipette solutions containing 600 and 803 nM [Ca2+] were almost equal to the ratios obtained extracellularly from internal solutions of identical compositions, but in experiments using pipette solutions having lower [Ca2+] the intensity ratios measured in myocytes were higher than those obtained extracellularly. 4. If the membrane was depolarized or hyperpolarized, the fluorescence ratio either increased or decreased, respectively. These changes in the fluorescence ratio were virtually blocked by the extracellular application of 2 mM-Ni2+. 5. When the concentration of bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) in the recording pipette was reduced from 30 to 1 mM, an increase in [Ca2+]i was observed during a depolarizing ramp pulse. The Ca2+ influx estimated by integrating the 2 mM-Ni(2+)-sensitive current during the pulse correlated with the increase in [Ca2+]i estimated from Indo-1 using the extracellular calibration curve, but the values of the influx determined directly from Indo-1 fluorescence were always larger than those calculated from the exchanger current.(ABSTRACT TRUNCATED AT 400 WORDS)