Characteristics of the entry process for sodium in transporting epithelia as revealed with amiloride.
1. The permeation of sodium ions trhough the mucosal surface of frog skin epithelium at different transepithelial potentials has been investigated using the blocking drug amiloride. 2. An increase in serosal negativity in voltage-clamped skins was associated with an increase in the absolute amount of inhibition caused by a fixed concentration of amiloride. Hyperpolarizing or depolarizing skins with respect to the short-circuited condition did not affect the apparent affinity of amiloride for the entry sites. 3. When skins were voltage clamped at -50 mV (serosa negative) the specific binding of amiloride to sodium entry sites was increased by 77% compared to the short-circuited condition. Skins clamped at +50 mV had only 72% of the specific binding found in short-circuited skins. Experiments with a second blocking drug, triamterene, indicated that the extra binding sites appearing at -50mV were similar to those found under short-circuit conditions. The appearance and disappearance of binding sites may reflect changes in cell volume. 4. The findings suggest that the increased sodium current which flows when skins are clamped at -50 mV results from an increase in the number of entry sites, and perhaps also to a voltage sensitive increase in flux through each entry site. (+info)
Prolonged exercise after diuretic-induced hypohydration: effects on substrate turnover and oxidation.
To determine the influence of a diuretic-induced reduction in plasma volume (PV) on substrate turnover and oxidation, 10 healthy young males were studied during 60 min of cycling exercise at 61% peak oxygen uptake on two separate occasions > or =1 wk apart. Exercise was performed under control conditions (CON; placebo), and after 4 days of diuretic administration (DIU; Novotriamazide; 100 mg triamterene and 50 mg hydrochlorothiazide). DIU resulted in a calculated reduction of PV by 14.6 +/- 3.3% (P < 0.05). Rates of glucose appearance (R(a)) and disappearance (R(d)) and glycerol R(a) were determined by using primed constant infusions of [6,6-(2)H]glucose and [(2)H(5)]glycerol, respectively. No differences in oxygen uptake during exercise were observed between trials. Main effects for condition (P < 0.05) were observed for plasma glucose and glycerol, such that the values observed for DIU were higher than for CON. No differences were observed in plasma lactate and serum free fatty acid concentrations either at rest or during exercise. Hypohydration led to lower (P < 0.05) glucose R(a) and R(d) at rest and at 15 and 30 min of exercise, but by 60 min, the effects were reversed (P < 0. 05). Hypohydration had no effect on rates of whole body lipolysis or total carbohydrate or fat oxidation. A main effect for condition (P < 0.05) was observed for plasma glucagon concentrations such that larger values were observed for DIU than for CON. A similar decline in plasma insulin occurred with exercise in both conditions. These results indicate that diuretic-induced reductions in PV decreases glucose kinetics during moderate-intensity dynamic exercise in the absence of changes in total carbohydrate and fat oxidation. The specific effect on glucose kinetics depends on the duration of the exercise. (+info)
Two cases of pseudoaldosteronism (Liddle's syndrome) in siblings.
Two cases of Liddle's syndrome were found in a brother and sister. Both showed typical hypokalemic hypertension without hyperaldosteronism. These cases showed similar responses in various pharmacological tests and their symptoms of hypokalemic and hypertension were relieved by triamterene. And in a family survey, the father appeared to be affected. This seems to be the first report on this syndrome in Japan. (+info)
Determination of hydrochlorothiazide, triamterene and propranolol hydrochloride by the spectrophotometric method and high-performance liquid chromatography (HPLC).
Spectrophotometric and chromatographic (HPLC) methods for determination of hydrochlorothiazide, triamterene and propranolol hydrochloride were elaborated. Both methods were appropriate for the determination of three compounds in pharmaceutical preparations containing their mixtures. Both the elaborated methods for the determination of the studied compounds give comparable results and can successfully be applied to the assay in their mixtures occurring in the composition of pharmaceutical preparations. (+info)
Acetazolamide-induced muscle weakness in hypokalemic periodic paralysis.
A 46-year-old man with hypokalemic periodic paralysis (HypoPP) and diabetes mellitus (DM) had worsened muscle weakness after acetazolamide (ACZ) treatment. During the paralytic episode, serum potassium levels were reduced, and serum chloride and insulin levels were increased. The data suggested proximal renal tubular acidosis due to ACZ. We determined arterial-venous concentrations of potassium, insulin and glucose across the forearm. Venous potassium levels were markedly reduced. ACZ is thought to potentiate potassium uptake into muscles. Hyperinsulinemia and DM could contribute to ACZ-induced exacerbation in our patient. We should pay more attention to ACZ-treated HypoPP patients with hyperinsulinemia and DM. (+info)
Effect of triamterene on leucocyte sodium and potassium levels in heart disease.
Sodium and potassium levels in plasma and leucocytes and the sodium efflux rate constants of leucocytes were measured in patients with congenital heart disease not on treatment, patients with valvular heart disease being treated with digoxin and conventional diuretics, and patients with valvular heart disease receiving digoxin and either conventional diuretics or triamterene or both. The group being treated with digoxin and conventional diuretics showed low cellular potassium levels, low sodium efflux rate constants, and a rise in cellular sodium levels. Patients given triamterene showed a rise in potassium levels in plasma and cells and in the sodium efflux rate constant. (+info)
CLINICAL EXPERIENCE WITH A NEW DIURETIC, TRIAMTERENE, IN CONJESTIVE HEART FAILURE.
Triamterene therapy was evaluated in 35 patients with congestive heart failure over a period of two and one-half years. The parameters used were: clinical assessment; daily 24-hour urine sodium, potassium, chloride, and total volume; bi-weekly serum sodium, potassium, chloride, uric acid, and SGOT; hemogram, and BUN.Triamterene is a moderately potent diuretic and natriuretic, with the added desirable property of potassium conservation. It acts synergistically with spironolactone and not only potentiates the effects of hydrochlorothiazide but greatly minimizes its kaluretic effect.It is particularly useful in patients in whom cardiac arrhythmias are associated with digitalis intoxication or with inadvertently induced hypokalemia. Its main therapeutic value, used either alone or in combination with other diuretics, is in the longterm management of chronic edema, especially in certain patients refractory to the currently used diuretics.No significant undesirable side effects were noted. (+info)
RESPONSE OF THE INFANT KIDNEY TO DIURETIC DRUGS.
The diuretic response of normal infants, 6 to 47 days of age, to single doses of mercaptomerin, chlorothiazide, acetazolamide, triamterene and spironolactone was studied by following urinary electrolytes, pH and osmolality. Peak diuresis occured two to four hours after drug administration, and because of compensatory mechanisms little change in urinary excretion was found if only 24-hour urines were studied. Mercaptomerin increased sodium excretion seven-fold, compared to three- to four-fold increases for the other diuretics. Control urinary Na:K ratios averaged 0.68 in infants compared to 2.8 for adults, and mercaptomerin produced the largest increase in this ratio. Qualitatively the response to diuretics is the same in newborn in the ages studied as it is reported to be for adults; no immaturity of the infant kidney in this regard was demonstrated. (+info)