Relationship of chemically initiated enzyme secretion to metabolism in rat parotid in vitro

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 microgram DNA per min and in each case this was increased approx. 2.4-fold under stimulation by carbachol (10 microM) and approx. 3.1-fold by adrenaline (10 microM). Isoprenaline (10 microM) 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.

The effects of theophylline and 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (RO 20-1724) on protein secretion from rat parotid gland

1 The effects of two chemically distinct cyclic nucleotide phosphodiesterase (PDE) inhibitors on protein secretion from superfused rat parotid gland were studied.2 In the presence of 1.0 mM Ca(2+), Ro 20-1724 (10 muM), an imidazolidinone derivative, increased the secretory response to isoprenaline 100% and the isoprenaline-dependent accumulation of adenosine cyclic 3',5'-monophosphate (cyclic AMP) 300-400%. At this concentration Ro 20-1724 alone did not cause protein secretion, accumulation of cyclic AMP or significantly inhibit PDE activity in cell-free preparations from parotid gland.3 In the absence of added Ca(2+) and in the presence of 1.0 mM EGTA, Ro 20-1724 inhibited the secretory response to isoprenaline 65% while increasing isoprenaline-dependent cyclic AMP accumulation 200%.4 In the presence of Ca(2+), theophylline (10 mM) stimulated protein secretion but did not cause the accumulation of cyclic AMP. When combined with isoprenaline the rate of secretion was greater than the sum of the effects of the individual drugs but there was no effect of theophylline on the isoprenaline-dependent accumulation of cyclic AMP.5 Theophylline-stimulated protein secretion is increased by omitting Ca(2+) from the superfusion medium without any detectable change in cyclic AMP accumulation. Under these conditions Ro 20-1724 inhibits theophylline-stimulated protein secretion and the maximum rate of protein secretion in the presence of isoprenaline and theophylline is no greater than that seen with either agent alone.6 It is concluded that the theophylline effects do not result from inhibition of PDE. It is suggested that the primary action of both drugs on parotid gland acinar cells is to alter the distribution of intracellular Ca(2+). Ro 20-1724 may also inhibit Ca(2+)/calmodulin activated enzymes such as PDE.

[Clinical aspects of non-tumorous diseases of the salivary glands]

The vast field encompassed by the non-tumorous diseases of the salivary glands poses difficult problems for their diagnosis and therapy. In order to facilitate comprehension of the pathological processes and the therapeutical possibilities for their treatment, physiological and biochemical aspects of salivary gland function are presented in the introduction. There are also mentioned in detail most of the diagnostic methods clinically applied today and stress is laid on their respective diagnostic values. In contrast to the opinion of many authors, exploratory excision and puncture are shown to be very important diagnostic tools in salivary gland pathology. The specific application of these methods is often the only means for a reliable diagnosis. The classification of the diseases follows Seifert's (1971) proposal. The chronic diseases of the salivary glands are specifically mentioned with the chronic recurrent and the chronic myoepithelial sialoadenitis taking first place. The sialoses are presented in a larger chapter. An attempt was made to correlate clinical and experimental results, to establish working hypotheses concerning the development of sialoses, to suggest therapeutical possibilities and, last not least, to give an idea of the many clinical and patho-anatomical difficulties to be overcome for a satisfactory understanding of such pathological processes. Finally, various forms of salivary gland fistulas and their treatment are mentioned. The long list of references merely gives an approximation of the abundance of publications dealing with the problems of this field.

Continuous in vitro measurement of mouse salivary gland enzymes

A perifusion chamber technique is described that permits continuous measurement of the in vitro release of salivary enzymes from slices of mouse salivary glands responding to various stimuli. Kinetics of amylase secretion differed from those of esterase, which suggests that the secretory processes differ for these two enzymes.