LLC-PK1 mutant with increased Na+-H+ exchange and decreased sensitivity to amiloride

LLC-PK1 cells contain a well-characterized Na+-H+ antiporter that is sensitive to ethylisopropylamiloride (EIPA) in the submicromolar range. Using a modification of the method of Franchi et al. (J. Biol. Chem. 261: 14614-14620, 1986), we have selected mutants that can recover from an acid load in the presence of 100 microM EIPA. One such mutant, designated PKE20, has been studied in detail. The maximal velocity (Vmax) for the Na+-H+ antiporter, assayed as EIPA-sensitive 22Na+ uptake, has increased from 44 nmol.min-1.10(6) cells-1 in the parent cells to 106 nmol.min-1.10(6) cells-1 in PKE20. No detectable change has occurred in the Km for Na+ (118 mM in the parent, 111 mM in the mutant) or in the dependence of Na+ uptake on intracellular pH. However, the PKE20 antiporter exhibits a greatly decreased sensitivity to amiloride and its derivatives, with drops in inhibitory potency ranging from 25-fold (amiloride) to 100-fold (EIPA). The mutation is specific for the antiporter; measurements of Na+-K+ pump and Na+-dependent amino acid uptake show only small changes, which appear to result from minor antiporter-induced alterations in internal Na+ concentration. PKE20 cells should prove useful in experiments to identify and isolate the antiporter protein.

Manipulation of ascitic fluid pressure in cirrhotics to optimize hemodynamic and renal function

Intra-abdominal pressure (IAP), measured via a transurethral catheter, hemodynamic, and renal functions were evaluated in 25 cirrhotic patients admitted to ICU with variceal bleeding, tense ascites, and peripheral edema. In patients with an IAP greater than 25 cm H2O, a paracentesis was performed to decrease the IAP by 10 cm H2O. After paracentesis, a decrease in the IAP from 33.47 to 19.06 cm H2O (p less than 0.001) resulted in a decrease in total peripheral resistance (TPR) (p less than 0.01) and a significant increase in cardiac index (CI) (p less than 0.001), stroke index (p less than 0.001), left ventricular stroke work (LVSW) (p less than 0.01), and right ventricular stroke work (p less than 0.01). The therapeutic effects of paracentesis on renal function were: a decrease in BUN and serum creatinine (p less than 0.001) and an increase in the creatinine clearance (Ccr) (p less than 0.001), urine volume (p less than 0.001), osmolar clearance (Cosm) (p less than 0.001), and urine creatinine (p less than 0.001) values. The IAP correlated directly with the TPR (r = +0.35, p less than 0.01) and inversely with the CI (r = -0.39, p less than 0.001) and LVSW (r = -0.37, p less than 0.001) in the 126 studies of IAP performed with the 25 patients. IAP also correlated directly with BUN (r = 0.40, p less than 0.001), serum creatinine (r = 0.28, p less than 0.01), and free water clearance (CH2O) (r = 0.3, p less than 0.001); IAP correlated negatively with Ccr (r = -0.54, p less than 0.001) and Cosm (r = -0.43, p less than 0.001). In critically ill cirrhotic patients, IAP, when measured noninvasively via a bladder catheter, is an accurate and useful method to follow manipulation of ascitic fluid pressure quantitatively in order to optimize hemodynamic and renal function.

Pharmacologically different Na/H antiporters on the apical and basolateral surfaces of cultured porcine kidney cells (LLC-PK1)

Proximal tubule cells of the kidney contain, on their apical surface, an amiloride-sensitive Na/H antiporter that functions in Na reabsorption and proton secretion. We have investigated the localization of the antiporter in a cloned cell line of porcine renal origin, LLC-PK1/Cl4, which is often considered to be a useful model of the proximal tubule. Transport measurements were performed with differentiated monolayers grown on Nuclepore filters, permitting independent access to the apical and basolateral cell surfaces. In control experiments with LLC-PK1/Cl4 monolayers, three marker transport systems showed the expected polarity: 87% of ouabain-sensitive Rb uptake was at the basolateral surface, and 99% of Na-dependent alpha-methylglucoside transport and 93% of Na-dependent D-aspartate (L-glutamate) transport were at the apical surface. By contrast, the monolayers displayed significant Na/H antiporter activity (assayed as ethylisopropylamiloride-sensitive 22Na uptake) at both cell surfaces, with an apical uptake rate amounting to 44% and a basolateral rate amounting to 56% of the total. Significantly, the apical and basolateral antiporters could readily be distinguished from one another on the basis of ethylispropylamiloride sensitivity. The apical system had an IC50 of 13 microM, close to that reported for kidney brush border vesicle preparations, whereas the basolateral system had an IC50 of 44 nM, similar to values seen in undifferentiated LLC-PK1 cells and other cultured cell lines. The PKE20 mutant, previously selected from LLC-PK1/Cl4 on the basis of resistance to ethylisopropylamiloride, was found to overexpress the more resistant antiporter both during rapid growth and on its apical cell surface at confluence; normal amounts of the more sensitive antiporter were seen on the basolateral surface of confluent PKE20 cells. Taken together, these results suggest that there are two distinct forms of the Na/H antiporter, which are under separate genetic control.

Pelvic fibromatoses--a rare gynecological entity

A rare case of pelvic fibromatoses is reported. This condition is rarely encountered in gynecological practice but when encountered, creates a diagnostic and therapeutic challenge. The reported patient highlights the difficulties encountered in surgical excision (done twice) and illustrates the local aggressive growth behavior of this entity.

Systemic complications of acute pancreatitis

The multisystem involvement in acute pancreatitis (AP) is a reflection of the pancreatic gland's capacity to produce a number of potent vasoactive peptides, hormones, and enzymes. The various prognostic criteria are early evaluations of these metabolic derangements. The pathogenesis of hypocalcemia, long recognized as an indicator of severity of AP, is multifactorial. Imbalances of parathyroid hormone (PTH)-calcitonin, the interactions of glucagon, gastrin and other pancreatic hormones with PTH-calcitonin, the role of free fatty acids in binding serum calcium with albumin, and the translocation of calcium ion in muscles and liver, have been recently described but remain conflicting theories. Yet, the time-honored theory of calcium-soap formation enjoys wide acceptance. Hyperglycemia, hypoglycemia, and occasional ketoacidosis in acute pancreatitis have been studied thoroughly. The complex cause-and-effect relationship between hyperlipidemia with acute pancreatitis needs further study. The coagulation abnormalities seem to be initiated by activated trypsin, and their role in microvascular coagulation appears to form a unifying hypothesis for major organ dysfunction, but this requires further investigation. Adult respiratory distress syndrome may be the result of active enzymes that digest pulmonary surfactant and/or microvascular thrombosis. The depression of cardiac function and shock are suspected to be secondary to vasoactive peptides such as bradykinin, or myocardial depressant factor, whose structure has yet to be elucidated. The renin-angiotensin alterations and renal complications in acute pancreatitis have received scant attention in the literature. The onset of moderate visual disturbances, or even blindness, in a patient with acute pancreatitis as a result of retinal vessel thrombosis is fortunately uncommon. Rare but interesting are the manifestations such as subcutaneous fat necrosis, arthralgia, and pancreatic encephalopathy. Despite the extensive literature on the complexities of the pathogenesis of complications of acute pancreatitis, there have been very few advances in the prevention and management of specific complications. It is hoped that further work on modification of enzymatic disturbances induced in acute pancreatitis will result in its effective treatment and prevention of serious complications.

Overinflation of pneumatic antishock garments in the elderly

The hemodynamic effects of pneumatic antishock garment application in high-risk elderly patients were examined in 10 preoperative patients (mean age 66.5 +/- 6.4 years) with the pneumatic antishock garments uninflated, after 15 minutes of inflation to 50 mm Hg, and after 15 minutes of inflation to 75 mm Hg. After inflation, significant increases in right atrial pressure (89 percent), pulmonary capillary wedge pressure (34 percent), and mean pulmonary artery pressure (21 percent) were noted. Mean peripheral arterial pressure increased 11.2 percent. Depression of the cardiac index (18 percent), left ventricular stroke work (20 percent), and right ventricular stroke work (16.4 percent) with associated increases in total peripheral resistance (26 percent) and pulmonary vascular resistance (18 percent) occurred in 5 of 10 patients. Left ventricular function curves revealed a progressive decrease in ventricular function at 50 mm Hg and 75 mm Hg. We have concluded that the effect of the pneumatic antishock garment on myocardial function is variable and unpredictably dangerous in the elderly patient with diminished myocardial reserve. As no significant benefit was derived from inflation pressures greater than 50 mm Hg in these patients, the lowest combination of pressures producing the most efficacious results should be used.

Effect of administration and withdrawal of oral contraceptive pills on serum lipids and lipoproteins

We studied the effects of oral contraceptive pills (OCP) supplied by the Govt of India in its Family Welfare Campaign, on serum lipid levels of women. The OCP, containing 30 micrograms ethinyl estradiol and 1 mg of norethisterone acetate were administered to the women for six months continuously and serum lipid levels were estimated after three and six months of the treatment. There were no significant changes in serum cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), serum triglycerides and very low density lipoprotein (VLDL). In a simultaneous study we also measured serum lipid levels at 3 and 6 months after withdrawal of the pills in women who had been receiving OCP containing 50 micrograms of ethinyl estradiol and 0.5 mg of one of the progesterones for the past 1 1/2 to 2 years continuously. Only serum LDL level fell significantly (P less than 0.01) on 3 months withdrawal period. It is concluded that 6 months of usage of the OCP marketed by the Govt. of India does not affect the serum lipid profile.

Stimulation by serum of the Na+/H+ antiporter in quiescent pig kidney epithelial (LLC-PK1) cells and role of the antiporter in the reinitiation of DNA synthesis

LLC-PK1 cells can be brought into a classical quiescent state by depriving them of serum for 6 days. At this time, pulse-labeling with [3H]-thymidine shows that only 3% of the cells are synthesizing DNA, but the quiescent cells can be stimulated with serum to re-enter the cell cycle at a point early in G1. The rate of amiloride-sensitive 22Na+ uptake (as a measure of the Na+/H+ antiporter) is relatively low during quiescence; it rises 2- to 3-fold within 4 h after serum addition. This increase in antiporter activity appears to be required for the resumption of DNA synthesis in the absence of bicarbonate, because ethylisopropylamiloride (EIPA) blocks [3H]-thymidine incorporation when serum is added to cells in bicarbonate-free medium. In the presence of bicarbonate, however, EIPA has no effect on [3H]-thymidine incorporation, indicating that another (bicarbonate-dependent) transport system can substitute for the antiporter under these conditions.

Synthesis and metabolic disposition of 14C-centperazine in rats

The metabolic disposition of [2-14C]-centperazine (1; 3-ethyl-8-methyl-1,3,8-triazabicyclo[4.4.0]decan-2-one) following an injection of 5 mg/kg dose was studied in male albino rats. During the initial period of 45-60 min, a very rapid fall in blood level of radioactivity was noticed. Thereafter the rate of fall of blood radiocarbon went on decreasing but did not attain linearity even upto 24 h. The drug was found to be fairly distributed in all the tissues attaining highest concentration in most of them within 30 min. In 24 h, about 83.5% of the administered drug was eliminated from the body, of which 21.3% was recovered from the faeces and 61.1% from the urine. The 14CO2 accountes for only 1% of the total dose. The drug exhibited significant binding with all the tissues examined. The brain and muscle showed highest and lowest activity, respectively.