Mechanisms of respiration intensification of rat pancreatic acini upon carbachol-induced Ca(2+) release

Acta Physiol (Oxf). 2013 Aug;208(4):387-99. doi: 10.1111/apha.12119. Epub 2013 Jun 11.

Abstract

Aim: Acetylcholine as one of the main secretagogues modulates mitochondrial functions in acinar pancreacytes, presumably due to increase in ATP hydrolysis or Ca(2+) transport into mitochondria. The aim of this work was to investigate the mechanisms of carbachol (CCh) action on respiration and oxidative phosphorylation of isolated pancreatic acini.

Methods: Respiration of intact or permeabilized rat pancreatic acini was studied at 37 °C using a Clark oxygen electrode.

Results: Respiration rate of isolated acini in rest was 0.27 ± 0.01 nmol O2 s(-1) 10(-6) cells. Addition of 10 μM CCh into respiration chamber evoked biphasic stimulation of respiration. Rapid increase of respiration by 20.1% lasted for approx. 1 min, followed by decrease to level by 11.5% higher than control. Addition of 1 μm CCh caused monophasic increase by 11.5%. Preincubation (5 min) with 1 or 10 μm CCh elevated respiration rate by 12.5 or 11.2% respectively. FCCP prevented the effect of CCh. Preincubation with 1 (but not 10) μm CCh increased FCCP-uncoupled respiration rate. Thapsigargin slightly elevated respiration, but ryanodine did not. Application of 2-aminoethoxydiphenyl borate or ruthenium red prevented the effects of CCh on respiration, while oligomycin abolished them. Preincubation with 1 μm CCh prior to cell permeabilization increased respiration rate at pyruvate+malate oxidation, but not at succinate oxidation. In contrast, preincubation with 10 μm CCh decreased pyruvate+malate oxidation.

Conclusion: Medium CCh dose (1 μm) intensifies respiration and oxidative phosphorylation of acinar pancreacytes by feedforward mechanism via Ca(2+) transport into mitochondria and activation of Ca(2+) /ADP-sensitive mitochondrial dehydrogenases. Prolonged action of high CCh dose (10 μm) might impair mitochondrial functions.

Keywords: Ca2+; carbachol; mitochondria; pancreatic acini; respiration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Calcium / metabolism*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Carbachol / pharmacology*
  • Citric Acid Cycle / physiology
  • Male
  • Oxygen Consumption / physiology*
  • Pancreas / metabolism*
  • Rats

Substances

  • Carbachol
  • Calcium