Dynamic Changes in the Rate of Amylase Release Induced by Various Secretagogues Examined in Isolated Rat Parotid Cells by Using Column Perifusion.

Abstract

Isolated parotid acinar cells were perifused in small columns by embedding them in Bio-Gel P-2 beads as an inert supporting matrix, and the effect of carbamylcholine, substance P, and isoproterenol on the rate of amylase release was examined by measuring amylase activity in the effluent. Amylase release by continuous stimulation with carbamylcholine and substance P was biphasic. They caused a rapid and large increase in the rate of amylase release that reached maximum 30 to 60s after the onset of stimulation, followed by a rapid decline to a lower sustained level that was maintained as long as the agonists were present. The rapid decline in the rate of amylase release was due to rapid development of refractoriness. Repeated 1 min pulse stimulation with these secretagogues showed that recovery from refractoriness was also rapid in onset, and 1 min of washout was sufficient to cause significant recovery from refractoriness for both carbamylcholine and substance P. Recovery, however, was not complete after 10 min of washout. Amylase release by continuous stimulation with isoproterenol, on the other hand, developed more slowly with the peak rate being attained at about 6 min after the onset of stimulation. Refractoriness was not observed in the effect of isoproterenol. The maximum effect in the rate of amylase release attained by carbamylcholine or substance P was higher than that by isoproterenol. These results suggest that the apparent small effect of carbamylcholine and substance P on amylase release reported earlier by using batch systems is probably due to the rapid development of refractoriness to these secretagogues, but not to isoproterenol.

Vesicle Associated Membrane Protein 8 (VAMP8)-mediated Zymogen Granule Exocytosis Is Dependent on Endosomal Trafficking via the Constitutive-Like Secretory Pathway

“…Acini Perifusion-Isolated acini were suspended in 1 ml of Bio-Gel P2 beads and perfused at a rate of 1 ml/min at 37°C using a peristaltic pump as previously described (38,39). Samples were collected each min over 20 min for amylase analysis.…”

“…Using a perifusion system to monitor secretion from a single group of cells over time demonstrates secretion initially peaks at 1 min and decreases over 2-3 min followed by a second prolonged phase that peaks and declines to near the initial constitutive levels over 20 min (Fig. 3A) (38,39). In VAMP8 Ϫ/Ϫ acini the initial rapid phase is slightly delayed by 1 min then quickly decays to constitutive levels by 3-5 min (see the dotted line) followed by a further decrease that approaches the constitutive levels seen in WT acini.…”

Effect of Oxidative Stress on Secretory Function in Salivary Gland Cells

“…Although -receptor stimulation dominantly provokes amylase release, stimulation of VIP and muscarinic receptors also evokes amylase release via the increases in intracellular cAMP and Ca 2+ concentrations, respectively, in rat parotid acinar cells (Scott & Baum, 1985;Yoshimura & Nezu, 1991). Then we next examined the effect of ethacrynic acid on amylase release induced by VIP and carbachol, a muscarinic agonist.…”

Simulation of Regulated Exocytosis of Amylase from Salivary Parotid Acinar Cells by a Consecutive Reaction Model Comprising Two Sequential First-order Reactions

“…Intracellular calcium also induces small amounts of amylase secretion (Putney, 1986;Yoshimura & Nezu, 1992). Yoshimura et al developed a perfusion system which shows the velocity of amylase release in 30 s increments (Yoshimura & Nezu, 1991;. Results with this system clearly indicated that the time courses of secretion induced by cAMP-producing agonists and calciummobilizing agonists are di!erent and characteristic: secretion by the cAMP-producing agonist isoproterenol (IPR) increases gradually to reach maximum about 5 min after the onset of FIG.…”