The pH EpiStat is a new device that works together with any of Physiologic Instruments Ussing systems – any model, any vintage up to 8 channels. The unit’s small footprint (30.5 cm x 13.3 cm x 25.5cm HxWxD) enables it to easily fit on the benchtop next to one of our  EasyMount Ussing Chamber systems. The unit is multichannel, allowing measurements from 1-8 channels almost simultaneously. The accompanying software, Acquire & Analyze Version 3.0, controls both the pH EpiStat and our voltage/current clamp instruments to enable concurrent measurements of bioelectric properties and acid or base flux across the epithelium.  

pH Stat Methodology

Measurement of acid/base transport across epithelial cells is similar to measuring the short-circuit current except that the pH, rather than voltage, is held constant. To accomplish this the pH of an unbuffered solution on one side of the epithelium is monitored while precise amounts of titrant (acid or base) are added to keep the measured pH constant. By knowing the exact volume of acid or base addition, time of addition and concentration of titrant required to “clamp” the pH, the software can calculate the rate of acid or base transport across the epithelium.

The pH EpiStat Model pH8 was engineered to accurately measure pH to within +/-0.002 pH units and inject precise volumes of titrant of less than 50nL and is controlled by the latest version of Acquire & Analyze (version 3). Together, titrant additions required to hold the pH constant are accurately tracked and the rate of acid/base transport across the epithelium is calculated.

High Content Transport Studies

Epithelial pH homeostasis is an important area in research. In virtually every tissue and organ system epithelial cells have been demonstrated to play a role in pH regulation. This regulation generally involves multiple mechanisms including active, passive and exchange transport systems. The pH EpiStat can measure the rate of acid/base transport. However, when combined with our voltage/current clamp device and the short-circuit technique, experiments can be designed to delineate, for example,  between the movement of an anion such as chloride compared to bicarbonate, or cation such as sodium movement compared to hydrogen ions. In research, time is money. By enabling simultaneous measurement of both bioelectric data and pH, the system becomes a true high-content tool, providing richer datasets and greater efficiency for the end-user.

The pH EpiStat comes well equipped with an automated titrator and syringe, customized pH electrodes, titrant line tubing, titrant container, specialized chamber caps, dual air valves, calibrator bath, calibration buffer, and Acquire and Analyze Version 3 Software along with two days of installation and training.

Included system components are: