Certain diuretic agents have been reported to modify salt taste function and increase sodium intake. Benzothiazides purportedly increase a users salt taste sensitivity while amiloride applied topically to the dorsal surface of the tongue reduces sensitivity to this taste. Such gustatory and dietary effects may compromise the efficacy of these medications. The purpose of this proposed investigation is to evaluate the effects of these two types of diuretics on (1) salt consumption, (2) salt taste sensitivity as well as the perceived intensity and preference ratings for suprathreshold salt stimuli (which have greater dietary relevance, and (3) salivary flow composition to ascertain the relationship between both salivary electrolyte and drug levels and salt taste thresholds. Subjects will include 75 healthy adults recruited by public advertisement. All will be administered either a thiazide or amiloride placebo and tested twice during the two week period prior to their randomization into the three treatment groups (i.e. Hydrochlorothiazide (50 mg/d), Midamor (5 mg BID), or continued on placebo). Drug use will continue for 8 weeks with testing sessions held at the end of weeks 2, 4, and 8. Following three additional weeks of placebo use, one final testing session will be conducted. Each individual's response to treatment will be closely monitored and anyone experiencing an adverse reaction to treatment will be dropped from the study. Testing sessions will include (1) collections of whole mouth unstimulated and stimulated saliva, (2) assessment of NaCl, sucrose and citric acid taste recognition thresholds via a forced-choice staircase procedure, (3) determination of perceived intensity ratings for NaCl and citric acid tastants via a magnitude matching procedure, (4) measurement of salt taste preferences by ratings for saline solutions on a visual analog scale and a food modification task, and (5) evaluation of blood pressure and general well-being. Blood samples will be obtained at the initial clinic visit and weeks 4, 8, and 13 to monitor potassium levels. Two one-day urine collections will be made by subjects at home the two days prior to each testing session and will be brought to the clinic for analysis of Na, K, and creatinine levels. Salivary samples will be analyzed for flow rate and concentrations of Na, K, Cl and amiloride. A better knowledge of the potential gustatory and dietary modifying properties of these widely prescribed diuretic agents should aid in the development of optimal therapeutic practices for patients requiring such treatment.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Communication Sciences and Disorders (CMS)
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Monell Chemical Senses Center
United States
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