Action of carbonic anhydrase inhibitors on gastric secretion

Abstract

In this paper we have studied the action of the Acetazolamide and Chlorothiazide in the gastric secretion of the cat.

Forty cats with «whole Stomach≪ were used respecting in some ones their vagal inervation and practicing in others the section of the vagi at the level of the neck; as a stimulant of the gastric secretion, an infusion of histamine was used durgastric secretion, the acetazolamide (intraduodenally or intravenously) and the chlorothiazide (intraduodenally) was administred.

The dosis of acetazolamide varied between 60 and 100 mg/kg. (intraduodenally) and between 30 and 120 mg/kg. (intravenously). Chlorothiazide dosis varied between 130 and 380 mg/kg. The extraction of gastric juice was verified every 30 minutes and in every sample the total volume free C1H and total acidity, were determined.

Acetazolamide produces in the majority of our cats an increase in the gastric secretion (Tables I and II). In cats suffering from bilateral vagotomy the acetazolamide produces a diminution of the gastric secretion in almost all of our cats (Table III). It is suggested that acetazolamide has a twofold action, a central stimulation which would be trasmited by the vagus and a peripheric inhibition manifested only with vagotomy. A similar double action was found by the author in past studies with the insulin and the serotonin.

In two of our cats with intact vagi the acetazolamide produces a diminution of the gastric secretion which is interpreted by a predominant action of the peripheric inhibition. This would speak for a competitive action between the two effects of the drug.

The chlorothiazide exerts a variable action in the gastric secretion. Either with bilateral vagotomy (Table V) as with intact vagi (Tabla IV) has been observed increases or diminution of the gastric juice volume.

Acetazolamide and chlorothiazide even though they are both inhibitors of the carbonic-anhydrase, act then differently upon the gastric secretion. This difference in their way of acting cannot be explained by the greater inhibitory strengh of the acetazolamide.

The action of the chlorothiazide is probably due to a variation in the composition of the plasma. This factor would also influence the acetazolamide action but in that case it would have a lesser importance than the one acting of the carbonicanhydrase.