CHAPTER 47 – Regulation of Potassium Excretion

Pharmacology of Ionic Channel Function: Activators and Inhibitors

To evaluate the effectiveness of extended lymph node dissection in gastric cancer, the relationship between the number of lymph nodes with metastasis and the long-term outcome was studied retrospectively in 761 patients who underwent curative resection with extensive lymph node dissection. The cumulative 5-year survival rate was 85.8% in patients without lymph node metastasis, 60.2% in those with 1–4 lymph nodes, 35.6% with 5–10 nodes, and 12.3% with 11 or more nodes involved. Concerning N2 or N3 patients in whom metastatic lymph nodes would have remained without extensive dissection, the 5-year survival rate was 70.5% in those with 1–4 lymph nodes involved and 44.0% with 5 or more lymph nodes involved when no serosal invasion was observed. It was 38.5% with 1–4 lymph nodes and 5% with 5 or more lymph nodes involved when serosal invasion was observed. These results suggest that extensive lymph node dissection is effective in gastric cancer patients without serosal invasion and, when only a few lymph nodes are involved, also in those with serosal invasion. However, it is not considered to be effective in patients with serosal invasion and metastasis to many lymph nodes. Combination therapies are thought to be required in such patients. © 1993 Wiley-Liss, Inc.

Prognostic value of the number of metastatic lymph nodes in gastric cancer with radical surgery.

A population of NG108-15 neuroblastoma cells resistant to doxorubicin (NG/DOXR) was established. The cells exhibited a multidrug resistance phenotype with cross-resistance to vinblastin and colchicine, overexpression of a 170 kDa membrane protein identified as P-glycoprotein and reversal of resistance by verapamil and quinine. Compared with NG108-15 cells, NG/DOXR cells showed an increase in Na+ current density and a decrease in cyclic-AMP-activated Cl- current density with no change in K+- and volume-sensitive Cl- current densities. As previously observed in NG108-15 cells, the vacuolar-type H+-ATPase inhibitors bafilomycin A1 and nitrate induced membrane depolarizations in NG/DOXR cells. The resting potentials of sensitive and resistant cells were not significantly different, but the depolarizations evoked by these agents were significantly larger in NG/DOXR than in NG108-15 cells. The resting membrane potential of NG/DOXR cells, but not that of NG108-15 cells, was depolarized by verapamil, and this effect was abolished by bafilomycin. The volume-sensitive Cl- currents of drug-sensitive and drug-resistant cells were inhibited by a decrease in intracellular pH from 7.3 to 6.8. Whereas bafilomycin prevents activation of Cl- currents in both drug-sensitive and drug-resistant cells, verapamil inhibited the Cl- current only in NG/DOXR cells. The results are discussed in terms of the roles of cytoplasmic pH and membrane potential in multidrug resistance.

Alterations of ionic membrane permeabilities in multidrug-resistant neuroblastoma x glioma hybrid cells.

Background: This randomized Phase III trial will evaluate whether the methylene blue-assisted technique is efficient for harvesting lymph nodes after radical surgery for gastric cancer. Methods/design: Patients that undergo distal or total gastrectomy with radical nodal dissection will be randomly assigned to Group A: the standard group, the lymph nodes (LNs) will be harvested from the fresh specimen immediately after surgery, or Group B: the methylene blue-assisted group, where the LNs will be harvested from specimens fixed with 10% buffered formalin with methylene blue for 48 hours after surgery. The primary endpoint is the ratio of the number of the harvested LNs per time (minute). The secondary endpoint is the number of harvested LNs. A 25% reduction in the ratio of harvested lymph-node/time (minute) was determined to be necessary for this test treatment, considering the balance between the cost and benefit. Retrospective data was used to estimate the ratio of the number of the harvested LNs per time (minute) to be 40/30 minutes in Group A. A 25% risk reduction and a rate of 40/22.5 minutes is expected in Group B. Therefore, the sample size required ensuring a two-sided alpha error of 5% and statistical power of 80% is 52 patients, with 26 patients per arm. The number of patients to be accrued was set at 60 in total, due to the likelihood of enrolling ineligible patients.

/pdf/a-methylene-blue-assisted-technique-for-harvesting-lymph-3cwtbl00ck.pdf

A Methylene Blue–assisted Technique for Harvesting Lymph Nodes After Radical Surgery for Gastric Cancer: A Prospective, Randomized, Controlled Study

The role of phosphorylation in modulating an inwardly rectifying ATP-regulated K+ channel with inward conductance of about 90 pS was examined using the patch-clamp technique on opossum kidney (OK) cells. The activity of the inwardly rectifying K+ channel observed in cell-attached patches rapidly declined (channel "rundown") upon excision of the membrane into inside-out patches in a control bath solution (3 mM Mg2+, ATP-free). The declined channel activity was partially restored by applying ATP to the bath, and the ATP-induced channel restoration reached the near maximal level at an ATP concentration of 3 mM. The channel activity maintained by 3 mM ATP in inside-out patches was inhibited by K-252a (10 microM), a nonspecific protein kinase inhibitor, or KT5720 (200 nm), a specific inhibitor of cyclic AMP (cAMP)-dependent protein kinase (PKA), and was further stimulated by the addition of a catalytic subunit of PKA (20 nM). In cell-attached patches, the channel activity was also inhibited by K-252a (10 microM) or KT5720 (200 nM). The application of dibutyryl-cAMP (100 microM) alone failed to enhance channel activity, but significantly stimulated channel activity after the pretreatment of cells with Ro-20-1724 (100 microM), an inhibitor of cAMP-specific phosphodiesterase. These results suggest that maintenance of the activity of ATP-regulated K+ channels in OK cells requires protein kinase-mediated phosphorylation with ATP-hydrolysis, and that phosphorylation is mainly induced by PKA.

Modulation of inwardly rectifying ATP-regulated K+ channel by phosphorylation process in opossum kidney cells.

The present study investigated basolateral K+ channels and their pH-sensitivity in isolated bullfrog proximal tubule cells by using the patch-clamp technique, and compared channel activity with the basolateral membrane potential (EM) and intracellular pH (pHi) monitored by using double-barreled H+-selective microelectrodes in perfused bullfrog proximal tubules. In the patch-clamp experiments, K+ channels with inward slope conductance of about 50 pS were observed in the basolateral membrane of isolated proximal tubule cells in cell-attached patches. Raising pH of the bath with HCO3--free HEPES Ringer solutions from 7.7 (control) to 8.2 in the presence of an H+ ionophore, FCCP (2 μM), enhanced channel activity to 126.4% of controls; lowering bath pH to 7.2 and to 6.7 reduced channel activity to 26.4 and to 1.7% of controls. Microelectrode experiments in bullfrog proximal tubules perfused with HCO3--free HEPES Ringer solutions showed that EM and pHi in control conditions of peritubular pH 7.7 without FCCP were −52.6mV and 7.45. Raising peritubular pH to 8.2 in the presence of FCCP (2μM) increased EM and pHi to −61.8mV and 7.73; lowering it to 7.2 and to 6.7 decreased EM and pHi to −28.6 mV and 7.25 and to −10.6 mV and 6.95. These results suggest that changes in EM in response to cellular alkalinization or acidification made by HCO3--free HEPES solutions are produced primarily by changes in activity of the pH-sensitive K+ channels.

Basolateral ph-sensitive k+ channels mediate membrane potential of proximal tubule cells in bullfrog kidney

Using double-barreled K(+)-selective or conventional voltage microelectrode, K+ permeability of the luminal membrane of renal proximal tubule was investigated in comparison with that of the peritubular membrane in doubly-perfused bullfrog kidneys. A decade change in K+ concentration of the luminal perfusate from 3.5 (control) to 35 mM (high K+) induced depolarization in the luminal membrane potential by 11.2 mV with a slight elevation of intracellular K+ activity, (K)i, while those of the peritubular perfusate depolarized peritubular membrane potential by 31.6 mV with a moderate rise of (K)i by 8.0 mEq. The transport number for K+ (tK) in the luminal membrane was about one-third of that in the peritubular membrane. Both luminal and peritubular administrations of Ba2+ (4 mM) additively depolarized membrane potential. The magnitude of Ba2(+)-induced depolarization in the luminal membrane was about one-fourth of that in the peritubular membrane. The high K(+)-induced depolarization elicited from one-side perfusion was hardly affected by Ba2+ which was given from the other side. From these results we conclude that the transport number of K+ in the luminal and peritubular membranes of the proximal tubular epithelium is in the range of 0.17-0.32 and 0.52-0.66, respectively.

Potassium permeability of luminal and peritubular membranes in the proximal tubule of bullfrog kidneys.

Intravenous reinfusion of autogenous ascitic fluid was primarily applied for intractable ascites in the cirrhotic patient. Recently, this procedure was modified using a technique of cell removal and fluid concentration and applied for intractable ascites in the terminal cancer patient. In the present study, the effect of the reinfusion of cell-free and concentrated autogenous ascitic fluid for in-tractable ascites in the terminal cancer patient was evaluated. Fourteen cases of terminal cancer with intractable ascites were treated with 21 reinfusions. The reinfusion was effective in 85.7% of the cases decreasing the complaints caused by ascitic retension. It caused neither hypoprotenemia nor imbalance of serum electrolytes. In addition, the repeated reinfusion led to a restraint of the re-retension of ascitic fluid. Although pyrexia occurred in 71.4% of the reinfusions, in most of the cases, this was subsided with the administration of the usual antipyretics. These results indicate that the reinfusion of cell-free and concentrated autogenous ascitic fluid is useful for the control of intractable ascites in the terminal cancer patient.

Reinfusion of cell-free and concentrated autogenous ascitic fluid for intractable ascites in the terminal cancer patient

https://www.jstage.jst.go.jp/article/ringe1963/47/6/47_6_710/_pdf

A study of lymph node-metastases of gastric cancer using the methylene blue formalin fixing method

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