The effect of adenosine triphosphate on salivation in the dog

Abstract

SCHWARTZ, LASETER and KRAINTZ (1963) reported an enzymatic basis for active cation transport in the parotid gland of the dog. The enzyme, a magnesium dependent, sodium and potassium activated, microsomal adenosine triphosphatase (ATP-ase), is similar to the ATP-ase of the heart muscle but differed from that prepared from brain, liver, or kidney tissue. The mitochondrial fraction of parotid gland of sheep is also rich in ATP-ase activity (MANNI, GNLLO and AMBROSINO, 1956). The concentration of ATP in the parotid gland of the dog is markedly reduced after pilocarpine administration (GUBERNIEV, KOVYREV and RODZILLER, 1951). The addition of ATP at a level 50 mg/2*5 ml to the perfused submandibular gland of the dog results in the augmentation of pilocarpine-induced salivation (INOUE, 1958). In view of the evidence that ATP and ATP-ase may play a role in the secretory processes involved in salivation, it was of interest to determine whether ATP alone could induce salivation in the anaesthetized dog. The interpretation of results obtained from the study of effects of agents on salivation during pilocarpine-induced secretion has been criticized. Pilocarpine-induced saliva is not identical with that produced by electrical stimulation and the drug also has other systemic effects such as the release of catecholamines (BURGEN, 1964). This report deals with the effect of ATP on the induction of salivation in dogs anaesthetized with sodium pentobarbital (30 mg/kg). The studies were done on five mongrel male dogs weighing 15-20 kg. Wharton’s ducts and Stenson’s ducts were cannulated intra-orally with polyethylene tubing (PE 50). The left carotid artery was catheterized through the thyroid artery with a polyethylene cannula for the purpose of administering the ATP and also monitoring the blood pressure. The arterial blood pressure was measured with a Linear Core (E. & M. Instruments, Houston, Texas) transducer and the salivary flow rates determined with drop counters. The events were monitored with a multi-channel polygraph (Physiograph, E. & M. Instruments, Houston, Texas), ATP as a disodium salt was dissolved in 0.9% sodium chloride to give a concentration of 1 mg/ml. Studies were also made after administration of atropine sulphate 1.0 mg/kg. The ATP was administered into the carotid over a period of approximately 5 sec. It was found that the ATP was able to initiate both parotid and submandibular salivation at a level of 1 mg/kg. Saliva appeared only on the left side with the dosage used. This effect is illustrated by Fig. 1. In addition, a drop in