Autonomic regulation of secretion and transductal fluxes of ions and water was investigated in the rat parotid during stimulation with either acetylcholine bromide (ACh) or DL isoproterenol (IPR) infused intravenously. Samples of the primary secretory fluid (PSF) were obtained through micropuncture of the intercalated ducts, and their ionic composition was determined through microanalysis. In the IPR stimulated gland, the concentrations of K, Cl, and HCO3 of the PSF were markedly different from those in the ACh stimulated gland, suggesting different activity of the secretory process with each mode of gland stimulation. The transductal fluxes of ions were measured by simultaneous determinations of the ionic composition of the ductal fluid from the intercalated, lobular, and main ducts and calculations of the transductal fluxes of water through simultaneous measurements of amylase concentrations in the PSF and final saliva. In the IPR stimulated parotid, the net transductal reabsorptions of Na and Cl were lower than in the ACh stimulated gland, whereas the net transductal secretion of K was 4.43 times higher. The calculated ductal fluxes of HCO3 showed a net efflux of 0.265 μEq/min x 9 wt in the ACh stimulated parotid. In the IPR stimulated gland, the fluxes of HCO3 showed a reversal in direction, and a net influx of 0.466 μEq/min x 9 wt was observed. These data demonstrate that in the rat parotid gland both secretory mechanisms and transductal fluxes of ions are under specific autonomic control.
ASJC Scopus subject areas
- Physiology (medical)