Purine biosynthesis and excretion in Otala (=helex) lactea: An evaluation of the nitrogen excretory potential

Abstract

1. 1. The accumulation of uric acid, xanthine and guanine in estivating ] Otala lactea kidneys was used to estimate the rate of biosynthesis and deposition of the kidney purines in vivi. This estimated rate was 0.18 μmole purine per g total wt. per day. 2. 2. The rate of synthesis and deposition of the kidney purines in active snails was estimated by measuring the rate of incorporation in vivo of [1-C 14]glycine into the kidney purines. The highest observed rate was 0.68 μmole purine per g total wt. per day. 3. These estimated rates would account for the potential of excreting 9.7 mg N (693 μatom N)/kg total wt. per day as purine-N in estivating snails and 39.1 mg N (2793 μatom N)/kg total wt. per day in active snails. The term “recretion” is used here to apply to the depostion of the purines in the kidneys and not necessarily to their elimination from the body. 4. 4. Purines are the major nitrogenous excretory product of O. lactea since purine-N makes up roughly 90 per cent of the total N present in whole kidneys of both active and estivating snails. The only other major form of N eliminated by O. lactea is NH 3 gas. This was shown previously to arise from the action in vivo of tissue urease. From the estimated rates of purine-N excretion, the NH 3-N eliminated would account for no more than about 30 per cent of the total N excreted by estivating snails and no more than about 5 per cent of the total N excreted by active snails.