Rate of oxygen consumption by parotid atrophic acinar cells from rats fed liquid diet

Adult male rats were maintained on a nutritionally adequate liquid-diet or laboratory chow and water (control), for 9 days. They were then killed and the parotid glands removed. Enzymatically dispersed acinar-cell preparations were used to study rates of oxygen consumption (Qo2) using a Clark oxygen electrode. For both CON and LD cell preparations the basal Qo2 was 0.132 (±0.03–0.05) nmol O2 per μg DNA per min and in each case this was increased approx. 2.4-fold under stimulation by carbachol (10μM) and approx. 3.1-fold by adrenaline (10μM). Isoprenaline (10μM) elicited no significant increase in Qo2. Addition of ouabain (2.5 mM) or removal of Ca2+ from the extracellular medium prevented the action of carbachol to increase Qo2 over a sustained period. There were no significant differences in the basal, agonist-stimulated, or ouabain-sensitive Qo2 by dispersed acinar cells from liquid-diet rats compared to control. The results are consistent with the notion that liquid diet-induced atrophy represents a physiological adaptation rather than a pathological change. Nevertheless, they also indicate that in the acinar cells from liquid-diet rats the Na+/K+ ATPase is required to operate at normal levels of energy consumption despite the reduced acinar-cell volume and consequently lower levels of agonist-elicited transepithelial ion movements known to occur in these cells.