Tachykinins stimulate acid and pepsinogen secretion in the isolated porcine stomach

Abstract

To elucidate the underlying mechanism behind the thermogenic effect of adrenaline in human skeletal muscle, nine healthy subjects were studied during intravenous infusion of adrenaline. Restriction of blood flow to one forearm was obtained by external compression of the brachial artery, to separate a direct metabolic effect of adrenaline from an effect dependent on increased blood flow. The other arm served as the control arm. In the control arm, the forearm blood flow increased 4.7-fold (from 2.0 +/- 0.3 to 9.3 +/- 1.5 mL 100 g(-1) min(-1), P < 0.001) during the adrenaline infusion. Adrenaline significantly increased forearm oxygen consumption (from 4.7 +/- 2.1 to 7.0 +/- 3.6 micromol 100 g(-1) min(-1), P < 0.025). In the arm with restricted blood flow, the forearm blood flow increased 2.9-fold (from 1.6 +/- 0.3 to 4.6 +/- 0.8 mL 100 g(-1) min(-1), P < 0.002) but the forearm oxygen consumption did not increase (baseline period: 5.6 +/- 2.3 micromol 100 g(-1) min(-1), adrenaline period: 6.1 +/- 2.1 micromol 100 g(-1) min(-1), P = 0.54). The experimental design and the difficulties in interpretation of the result are discussed. The results give evidence for the hypothesis that the vascular system plays a key role in the thermogenic effect of adrenaline in skeletal muscle in vivo.

Protease‐activated receptor‐2 (PAR‐2) in the rat gastric mucosa: immunolocalization and facilitation of pepsin/pepsinogen secretion

“…Substance P and neurokinin A that can be released from the sensory neurons following PAR‐2 activation (Kawabata et al ., 2001a; Steinhoff et al ., 2000) are capable of stimulating secretion of pepsin in the stomach (Schmidt et al ., 1999). However, our experiments using capsaicin indicate that the PAR‐2‐triggered secretion of pepsin is independent of sensory neuronal activation.…”

Tachykinins in regulation of gastric motility and secretion

“…Electrical vagus stimulation enhanced the release of both SP and NKA in isolated vascularly perfused porcine antrum [13], isolated perfused porcine fundus/corpus [28] and vascularly perfused cod stomach [29]. A luminal release of SP has been shown in feline stomach in response to electrical vagus stimulation [30].…”

“…In cats with gastric fistula, on the other hand, SP stimulated acid secretion [75]. In isolated vascularly perfused porcine fundus/antrum, SP and NKA stimulated acid secretion [28]. The involvement of sensory nerve fibers in the regulation of acid secretion has been examined using capsaicin.…”

“…The effect involved NK-1 receptors [88,89]. In isolated vascularly perfused pig corpus/fundus, SP and NKA pig strongly stimulated pepsinogen secretion [28]. Given the fact that tachykininergic nerve fibers are often found in the vicinity of the gastric chief cells and that gastric release of tachykinins can be demonstrated in response to electrical stimulation of the vagal innervation of the pig stomach, the tachykinins should be considered potential regulators of pepsinogen secretion in this species.…”

“…Capsaicin increased somatostatin secretion, but this effect could be blocked by a CGRP antagonist, indicating that CGRP rather than the tachykinins are involved in the effect of capsaicin in isolated rat stomach preparations [93]. The involvement of tachykinins in regulating gastrin and somatostatin secretion in pig stomach was investigated using isolated perfused porcine antrum or corpus/ fundus preparations [28,94]. Infusions of SP and NKA decreased secretion of gastrin and increased secretion of somatostatin via NK-1 and NK-2 receptors.…”