Amino acid uptake in denervated rat parotid gland: I. Preparation and evaluation of a lobule system for in vitro studies.

The preparation and evaluation of an in vitro system to study the effects of denervation on amino acid uptake in the adolescent rat parotid gland are described. The biochemical consequences of denervation in adolescent rats were different from those seen in the adult. Surgical sympathectomy at 23 to 25 days resulted in marked decreases in weight (29%), acid-precipitable protein (21%) and alpha-amylase (50%) 2 weeks after surgery. Measurement of DNA indicated a loss of cells but no change in cell volume. These effects of sympathectomy were reversible, and these parameters had returned to control levels at 4 weeks. Parasympathetic denervation resulted in decreases in weight (48%), protein (20%) and alpha-amylase (30%) 2 weeks after surgery and paralleled those seen in the adult rat. Unlike sympathectomized glands, the deficits were not reversed at 4 weeks. Fluorometric measurement of norepinephrine and in vivo uptake of [3H]norepinephrine showed a large depletion at 2 weeks (80 and 84%, respectively). Auriculotemporal neurotomy (parasympathectomy), assessed by gas chromatographic measurement of acetylcholine, resulted in a 60% decrease in acetylcholine. The evaluation of a lobule preparation of these glands, suitable for short-term in vitro studies, is also described. Lobules were prepared by strictly mechanical means to avoid membrane changes reported in in vitro systems using enzymatically dissociated tissue. Histologic evaluation indicated that most lobules were free of mechanical damage, and normal secretory units were intact.(ABSTRACT TRUNCATED AT 250 WORDS)