Homeostatic Regulation of Membrane Potential by an Electrogenic Ion Pump against Change in the K+ Concentration of the Extra- and Intra-Organ Perfusion Solutions

The dependence of membrane potentials on changes in the extra-cellularK⁺ concentration [K⁺]_e was investigated in potato tuber sliceswith dripping perfusion, and in growing Vigna hypocotyl segmentswith pressurized intra-organ perfusion methods. Only under anoxiawere the membrane potential of potato tuber slices and the electricpotential difference between the parenchyma symplast and xylem(V_px) of Vigna hypocotyl segments depolarized markedly (46 mVand 42 mV/log[K⁺]_e unit, respectively) with increasing [K⁺]_eabove the critical values. The electric potential differencebetween the parenchyma symplast and organ surface (V_ps of thehypocotyl segments remained nearly unchanged up to 30 mEq [K⁺]_e.Under highly aerobic conditions the membrane potentials wererelatively independent of [K⁺]_e except at very high K⁺ concentrations.V_ps showed even hyperpolarization with the increasing KCl concentrationin the perfusion solution that is not in direct contact withthe surface membrane of the parenchyma symplast. The respiration-dependentelectrogenic components of the membrane potentials regularlyincreased with the increasing [K⁺]_e. A voltage-dependent homeostaticcontrol of membrane potential is discussed. (Received August 13, 1984; Accepted December 21, 1984)     

Characteristics of angiotensin II-, K+- and ACTH-induced calcium influx in adrenal glomerulosa cells. Evidence that angiotensin II, K+, and ACTH may open a common calcium channel

The characteristics of angiotensin II-, K+-, and adrenocorticotropin (ACTH)-induced calcium influx were studied in isolated adrenal glomerulosa cells. Basal calcium influx rate is 0.64 +/- 0.09 nmol/min/mg of protein. Addition of angiotensin II (1 nM) causes a rapid 230% increase in calcium influx rate. This angiotensin II-induced calcium influx is sustained and is rapidly reversed by angiotensin II antagonist, [Sar1,Ala8]angiotensin II. Addition of either K+ or ACTH (1 nM) causes a 340 or 160% increase, respectively, in the rate of calcium influx. The effect of either angiotensin II, K+, or ACTH on calcium influx is dependent on extracellular calcium. The apparent Km for calcium is 0.46, 0.35, and 0.32 mM, respectively. When the extracellular concentration of K+ is 2 mM, neither angiotensin II nor ACTH stimulates calcium influx. Conversely, when extracellular K+ is increased to 6 mM, both angiotensin II and ACTH cause a greater stimulation of calcium influx than at 4 mM K+. When extracellular K+ is increased to 10 mM, calcium influx is 360% of the basal influx seen at 4 mM K+, and neither angiotensin II nor ACTH further stimulates the influx rate. Nitrendipine (1 microM) blocks both angiotensin II- and K+-induced calcium influx completely. In contrast, 10 microM nitrendipine does not completely block ACTH-induced calcium influx. The calcium channel agonist, BAY K 8644, also stimulates calcium influx; 10 nM BAY K 8644 leads to a rate of calcium influx which is 185% of basal. This BAY K 8644-induced increase in calcium influx and that caused by either angiotensin II or ACTH are additive. In contrast, BAY K 8644 has more than an additive effect on the calcium influx when paired with 6 mM K+. These results suggest that angiotensin II, K+, and ACTH stimulate calcium influx via a common calcium channel but act by different mechanisms to alter its function.     

Congenital absence of flexor pollicis longus without hypoplasia of thenar muscles

A 7-year-old girl who was unable to flex her left thumb at the interphalangeal joint proved to have an extremely hypoplastic flexor pollicis longus with normal thenar muscles, which is very rare. The flexor digitorum superficialis of the ring finger was transferred to the inserting portion of the flexor pollicis longus tendon with good results. The patient's cooperation seems to be a factor determining the prognosis.     

Glycolipid composition of ascitic fluids from patients with cancer

The glycolipid composition of ascitic fluids from nine patients with cancer and one pleural effusion from a hepatoma patient was studied. Glucosylceramide, lactosylceramide, globotriaosylceramide, and globotetraosylceramide were found in all samples and also in normal human serum. These glycolipids accounted for more than 90% of the neutral glycolipid fraction and the composition in ascitic fluids was similar to that in normal human serum. From ascitic fluids, several minor glycolipids, which could not be detected in normal human serum, were isolated and characterized by exoglycosidase treatment. Lactoneotetraosylceramide was found in eight samples of ascitic fluids, and globopentaosylceramide was detected in two samples from hepatoma and one from pancreatic cancer. A fucolipid which was converted to lactoneotetraosylceramide by alpha-L-fucosidase treatment was recognized in two samples from hepatoma patients. In the ganglioside fraction, GM3 was the predominant component both in normal human serum and in ascitic fluid. The GM2 content in ascitic fluids was much higher than that in normal human serum. From these results, lactoneotetraosylceramide and GM2 are possible candidates as cancer markers, because they seemed to be derived from cancer tissues by shedding.     

Radioimmunoassay of urinary 3 beta-hydroxy-5-cholenoyl glycine in hepatobiliary disease

A radioimmunoassay for 3 beta-hydroxy-5-cholenoyl glycine in human urine has been developed. The antiserum was elicited with the antigen in which the steroid hapten is linked to a bovine serum albumin through the C-19 position. The [125I]-tyrosine derivative of the hapten was used as radioligand. The standard curves were linear ranging from 10 to 320 ng/mL. The cross-reactivities with other bile acids were not detectable and below 0.3% with cholesterol. Sample preparation includes extraction of 3 beta-hydroxy-5-cholenoyl glycine from urine and solvolysis of the sulfates--main form present in urine. Urinary excretion of 3 beta-hydroxy-5-cholenoyl glycine was 0.373 +/- 0.133 mumol/day in healthy adults. Urinary excretion of 3 beta-hydroxy-5-cholenoyl glycine increased in chronic liver dysfunction, hepatoma and obstructive jaundice in this order.     

Visible fibrinolysis by endothelial cells: Effect of vitamins and sterols

We have succeeded in corroborating the enhancing effect of vitamin A, vitamin C, sitosterol and fucosterol on the fibrinolytic activity of endothelial cells. The assay system consisted of anin situ dissolution of a fibrin layer coated onto a culture dish, over which endothelial cells were grown in a culture medium containing 10 % serum. The dissolution was enhanced by the addition of these vitamins and phytosterols to the culture medium.To whom correspondence should be addressed.     

Temporal patterns of protein phosphorylation after angiotensin II, A23187 and/or 12-O-tetradecanoylphorbol 13-acetate in adrenal glomerulosa cells.

The temporal patterns of protein phosphorylation in the adrenal glomerulosa cell were analysed by two-dimensional electrophoresis after stimulation with 10 nM-angiotensin II or various agents [10 nM-12-O-tetradecanoylphorbol 13-acetate (TPA), 50 nM-A23187, 1 microM-nitrendipine], administered singly or in combination. These patterns were compared with the temporal patterns of aldosterone secretion induced by the same agonists and antagonists. After 1 and 30 min of stimulation with angiotensin II, different patterns of protein phosphorylation were observed. A comparison of these patterns reveals that: the phosphorylation of only one protein was persistently enhanced during the continuous incubation with angiotensin II; the phosphorylation of five proteins was transiently enhanced (at 1 min but not 30 min); and the phosphorylation of three proteins did not occur at 1 min but was seen at 30 min. Addition of the phorbol ester TPA alone, which at 30 min is without effect in enhancing aldosterone production, has no effect on protein phosphorylation. The combined addition of TPA and the Ca2+ ionophore, A23187, which, like angiotensin II, evokes a sustained increase in aldosterone production, reproduced the temporal patterns of protein phosphorylation seen after angiotensin II action. Manipulations (A23187 alone, angiotensin II plus nitrendipine) which evoke only a transient rise in aldosterone production rate induce a transient rise in cellular protein phosphorylation. The 1 min patterns of phosphorylation seen after A23187 or combined angiotensin II and nitrendipine (a Ca2+ channel antagonist) are similar to those observed after 1 min of angiotensin II stimulation. These results suggest that, when angiotensin II acts, the initial cellular response is mediated by a different mechanism than that responsible for the sustained response.     

Effect of adriamycin entrapped by sulfatide-containing liposomes on ovarian tumor-bearing nude mice

Sulfatide-containing liposomes showed the highest degree of adriamycin entrapment of all the liposomes tested. Adriamycin was bound to the sulfatide anions on the liposomal membrane, inserted into the membrane, and incorporated into the aqueous compartment of the vesicle. Liposome-entrapped adriamycin was maintained at a much higher blood level than free adriamycin, and reached a lower concentration in the heart than did the free drug, which might lead to lower cardiotoxicity of the drug. Incorporation of adriamycin into ovarian tumor transplanted into nude mice was increased when entrapped by the sulfatide-containing liposomes. Liposome-entrapped adriamycin did not induce the drastic loss of body weight which occurred with the free drug. The growth of ovarian tumor was inhibited by liposome-entrapped adriamycin to the same degree as free adriamycin. Having these advantages, sulfatide-containing liposomes could be useful carriers of adriamycin for cancer chemotherapy.     

Preparation and antigenic property of methyl 3 beta-hydroxy-19-oxo-5-cholen-24-oate 19-(O-carboxymethyl) oxime-bovine serum albumin conjugate

The preparation and antigenic property of 3 beta-hydroxy-5-cholen-24-oic acid-bovine serum albumin (BSA) conjugate in which the hapten is linked to the carrier protein through an (O-carboxymethyl) oxime bridge at the C-19 position on the steroid nucleus is described. Antibody raised against antigen in the rabbit possessed high titer and specificity to 3 beta-hydroxy-5-cholen-24-oic acid, exhibiting no significant cross-reactions with various bile acids.