Related Experiment Video
Updated: Jul 21, 2026
13:55
Measurement of Vacuolar and Cytosolic pH In Vivo in Yeast Cell Suspensions
Published on: April 19, 2013
Defect in urinary acidification induced in vitro by amphotericin B
The Journal of Clinical Investigation
|March 1, 1970
Summary
Amphotericin B impairs urinary acidification by increasing bladder membrane permeability, leading to hydrogen ion back-diffusion. This study reveals the mechanism behind amphotericin B
Area of Science:
- Nephrology
- Urology
- Physiology
Background:
- Amphotericin B is an antifungal agent known to cause renal toxicity.
- The precise mechanism of amphotericin B-induced urinary acidification defects remains incompletely understood.
Purpose of the Study:
- To investigate the effect of amphotericin B on hydrogen ion secretion in the isolated turtle bladder.
- To elucidate the role of passive permeability changes in amphotericin B-induced acidification defects.
Main Methods:
- Induction of experimental urinary acidification defect using amphotericin B in isolated turtle bladders.
- Measurement of net hydrogen ion secretion under short-circuited conditions with controlled electrochemical forces.
- Assessment of ion permeability changes (K+, Na+, Cl-) induced by amphotericin B.
Main Results:
- Amphotericin B minimally affected hydrogen ion secretion when passive forces were minimized.
- Hydrogen ion secretion against a gradient was significantly reduced and abolished at higher gradients (>2 pH units).
- Amphotericin B markedly increased luminal membrane permeability to potassium and moderately to sodium and chloride.
Conclusions:
- Impaired acidification is primarily due to increased passive permeability and hydrogen ion back-diffusion, not active transport failure.
- The observed in vitro defect mechanism may explain renal tubular defects in patients treated with amphotericin B.
- This study highlights the importance of membrane permeability in regulating urinary acidification.
More Related Videos
11:14Visualization of Biofilm Formation in Candida albicans Using an Automated Microfluidic Device
Published on: December 14, 2017
08:30Preparation and Utilization of Freshly Isolated Human Detrusor Smooth Muscle Cells for Characterization of 9-Phenanthrol-Sensitive Cation Currents
Published on: January 31, 2020
Related Concept Videos
02:58Bronsted-Lowry Acids and Bases
The acid-base reaction class has been studied for quite some time. In 1680, Robert Boyle reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO2), and interact with alkalis to form neutral...
01:22Drug Elimination by Renal Route: Tubular Reabsorption
During the process of renal excretion, as the glomerular filtrate progresses to the distal convoluted tubule (DCT), drugs that are highly permeable, lipophilic, and nonionized undergo passive reabsorption from the tubular fluid into the surrounding peritubular capillaries. This reabsorption process restricts their elimination through the kidneys. However, the majority of drugs are either weak acids or weak bases, and their ionization level is dependent on pH. By altering the pH of urine, the...
01:08Titration of a Weak Acid with a Weak Base
Weak acids and bases do not undergo dissociation completely, and titrations between these two are rarely studied. When such studies are performed, say, for the titration of a weak acid with a weak base, the titration curve plots the change in pH as a function of the volume of base added. Take the titration of acetic acid with ammonia, for instance. During the titration, these two species form ammonium acetate and water, but the pH change is slow and gradual.
As a result, there is no simple...
As a result, there is no simple...
01:28Microbiota of the Urogenital Tract
The human urogenital system, once thought to be sterile in healthy individuals, is now recognized as a complex microbial habitat. Advancements in molecular sequencing techniques have revealed that even in healthy adults, the kidneys and bladder harbor microbial populations similar to those found in the distal urethra, albeit in much lower abundance. These resident microorganisms, while generally innocuous, can become opportunistic pathogens under conditions that alter the urogenital...
01:15Antifungal Agents
Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to cholesterol contributes to...