Correlations between transmural gastric potential difference and a well-known mathematical model.

After administration of several gastric irritants, time curves of the transmural gastric potential difference (GPD) were obtained. An attempt was made at fitting a mathematical function to these curves in order to facilitate and improve their evaluation. The Bateman function proved to be a useful description tool. In pharmacokinetics, this function is used amongst others for describing concentration profiles. For a total of 74 GPD curves, biexponential functions were fitted by the RIP-technique. The following irritants were administered: acetylsalicylic acid (ASA; 1000 mg, 500 mg, 250 mg), theophylline (480 mg, 350 mg), indomethacine (50 mg), and ethanol (20 ml, 40 v/v). The following results were obtained: The Bateman function is suitable for describing the observed biphasic time course of gastric potential difference, which includes lesion and restitution ("two compartment model"); correlation was high (r = 0.9). The curve parameters computed by this technique--area AUB, mean time, mean drop--are comparable to those obtained by pragmatic procedures (trapezoid rule). In particular, there is a distinct dosage-response relation between parameters correlated to irritating potency and the administered dose of ASA. Due to considerable interindividual variation of the parameters, ultimate assessment of their relationships to specific irritants could not be done.