Cumulative dose‐response curves for bethanechol‐induced electrogenic secretion in rat jejunum in vitro: is tachyphylaxis a significant factor?

Abstract

SUMMARYElectrogenic secretion was monitored as the short-circuit current (4,,)

Proctolin affects gut functions in lepidopteran larvae

“…This lack of effect could be related to a phenomenon of tachyphylaxis, which implies the desensitization of the presumptive proctolin‐sensitive receptors, as a consequence of their exposure for a long time interval (24 h) to a high dose of the agonist. Tachyphylaxis, originated by a prolonged high intensity stimulus or by a sequence of frequently repeated stimuli, has been observed in mammals for various gut receptors (Przyborsky et al. 1991; Thielemans et al.…”

Proceedings of the Physiological Society, 13-14 December 1991, Imperial College London Meeting: Communications

“…were mounted as sheets in newly designed Ussing-type chambers and incubated in bicarbonate saline. Secretory responses were monitored as short-circuit current by an automatic voltage current clamp (Przyborski et al 1991b). Cumulative dose-response curves for bethanechol were obtained over the range 5 x 10-2 to 10-6 M in the absence (control) and presence of varying concentrations of McN-A-343.…”

Assessment of receptor reserve during cholinergically induced intestinal secretion in rat jejunum in vitro

“…In brief, experiments were performed on pieces of mid-jejunum isolated from anaesthetized (pentobarbitone, 60 mg kg −" IP) male Wistar rats (Sheffield strain, 220-240 g). Each intestinal segment was stripped of its external muscle and cut along its anti-mesenteric border to produce a flat sheet of submucosa-mucosa which was clamped between Ussing-type chambers (Przyborski et al 1991 a). The exposed tissue area (1.92 cm#) was bathed continuously with 8 mL of warm (37 mC) Krebs bicarbonate saline which was oxygenated and stirred with humidified 95 % O # , 5% CO # by a gas lift mechanism built into the tissue mounting plates (Przyborski et al 1991 a).…”

“…Each intestinal segment was stripped of its external muscle and cut along its anti-mesenteric border to produce a flat sheet of submucosa-mucosa which was clamped between Ussing-type chambers (Przyborski et al 1991 a). The exposed tissue area (1.92 cm#) was bathed continuously with 8 mL of warm (37 mC) Krebs bicarbonate saline which was oxygenated and stirred with humidified 95 % O # , 5% CO # by a gas lift mechanism built into the tissue mounting plates (Przyborski et al 1991 a). In addition, the serosal solution contained 10 m glucose to support the metabolic requirements of the tissue and the mucosal solution 10 m mannitol as an osmotic balance.…”