Laboratory experience for understanding the physiological basis of diuretic therapy

T R Schwab, F G Knox
1991 Advances in Physiology Education  
R., ANDFRANKLYN G. KNOX. Laboratory experience for understanding the physiological basis of diuretic therapy. Am. J. Physiol. 260 (Adv. Physiol. Educ. 5): SlO-S13, 1991.--A combined lecture and laboratory experience was designed to enhance medical school students' understanding of the physiological basis of diuretic therapy. Studies are performed by students in anesthetized dogs to determine the effects of four clinically useful diuretics on renal function. The objective of the experience is to
more » ... he experience is to 1) learn the mechanisms of action, clinical indications, and adverse effects of diuretics; 2) review the renal physiology of glomerular filtration and sodium metabolism; and 3) complete analysis and interpretation of experimental data. These sessions provide an effective practical educational experience in applying the scientific method to begin to understand the physiology and pharmacology of diuretics. physiology education; pharmacology education; diuretics; renal function; student laboratory DIURETICS ARE AMONG the most commonly prescribed medications worldwide. Hypertension (6)) nephrotic syndrome (3)) hypercalciuric renal lithiases (11)) diabetes insipidus (Z), cerebral edema (9), and glaucoma (1) represent the diverse conditions in which diuretic therapy is useful. The second-year Mayo Medical School pharmacology curriculum has traditionally included one lecture encompassing the pharmacology of diuretics. Before the lecture each student is given a background reading assignment, "Sites of Mechanisms of Action in the Kidney and Effect on Monovalent Ion Excretion" in The Physiological Basis of Diuretic Therapy in Clinical Medicine (4). During the lecture the mechanisms of action, clinical uses, and adverse effects of each class of diuretic are sequentially presented in an order based on the principal site of action of the diuretic from the distal to the proximal nephron by a renal physiologist (F. G. Knox) and a nephrologist (T. R. Schwab). We have recently introduced a new laboratory experience that simultaneously accompanies this traditional lecture format to enhance medical student learning of the physiological basis of diuretic therapy. Our rationale for providing this added visual demonstration of pharmacology is based on the premise that the students' anticipation and excitement for experimentation improves their learning of clinically relevant subject matter. It also provides an important opportunity for the discus-sion of the use of animals in research. Our objectives for the students include 1) learning the mechanisms of action, clinical indications, and adverse effects of diuretics; 2) reviewing the renal physiology of glomerular filtration and sodium metabolism; and 3) completing experimental data analysis and interpretation using the scientific method. The specific aim of this laboratory experience is to determine the effects of four clinically useful diuretics on renal function in anesthetized dogs. Previous studies have suggested that renal diuretic and natriuretic responses are blunted during extracellular volume depletion (8). Therefore the present study was performed in the presence and absence of replacement of urinary volume and tested the hypothesis that volume replacement increases the renal effects of the distal nephron diuretic chlorthiazide, the ascending loop of Henle diuretic furosemide, the proximal nephron diuretic acetazolamide, and the proximal and distal nephron diuretic mannitol. METHODS Oueruiew. Students were assembled in the laboratory and divided into one of four preassigned diuretic groups and given a short orientation to this five-period protocol, including its purpose and their responsibilities. This was followed by the beginning of the didactic lecture and the protocol's first period. During the first period (placebo), we presented the physiological effects, clinical indications, and adverse effects of dietary sodium restriction and pharmacological aldosterone inhibition. During subsequent periods, we presented similar discussions for each diuretic (chlorthiazide, furosemide, acetazolamide, and mannitol) after its administration by the students. The effects of each diuretic on glomerular filtration rate, proximal and total nephron sodium reabsorption, and potassium and water excretion were determined. Students were asked to consider drug distribution, metabolism, and possible drug-drug interactions in interpreting the data that tested the hypothesis. Each student provided us with an anonymous response regarding the educational value of these 3-h sessions. Student assignments. Each second-year medical student was assigned to one of two groups of 20 students I wk before each session. Two separate 3-h sessions were held. In student group I, urinary losses during the protocol (see below) were intravenously replaced by equal SlO
doi:10.1152/advances.1991.260.6.s10 pmid:2058750 fatcat:mc6s6vqqnnawnfqs4wiesnklze