FACTORS INFLUENCING RENAL EXCRETION OF FOREIGN ORGANIC ACIDS

Renal excretory mechanisms for 16 organic acids (mostly benzoates) were examined by standard renal clearances in the dog to establish their participation in an active secretory system, and to ascertain the factors influencing their simultaneous tubular reabsorption. Active secretion was demonstrated by clearances greater than the glomerular filtration rate and by inhibition of excretion by presumably competitively transported acids, i.e., hippurates. Critical chemical substituents essential for transport could not be identified. For reabsorption by non-ionic diffusion, the relative roles of acidic strength, lipid solubility, and urinary pH are evaluated with emphasis on the variation in the importance of each of these factors.

EFFECTS OF ANTI-RHEUMATIC COMPOUNDS AND PYRIDINE DERIVATIVES ON THE CUTANEOUS RESPONSE TO THURFYL NICOTINATE IN THE GUINEA-PIG

The effects of certain anti-rheumatic drugs and compounds related to nicotinic acid on the cutaneous response to locally applied thurfyl nicotinate in guinea-pigs were investigated. Sodium salicylate, aspirin or phenylbutazone administered orally each reduced the response to thurfyl nicotinate at about half the dose needed for equivalent protection against the cutaneous effects of exposure to ultra-violet light. Nicotinic acid or thurfyl nicotinate given orally flushed the skin and reduced the intensity of the local reaction to thurfyl nicotinate without affecting the response to ultra-violet light. Nicotinamide, isonicotinic acid, picolinic acid and quinolinic acid were less effective in producing flushes and in reducing the effect of locally applied thurfyl nicotinate. The flush induced in guinea-pigs by oral nicotinic acid was reduced by the previous administration of phenylbutazone. Possible mechanisms for these effects are discussed.

DRUG-INDUCED CHANGES IN THE LIVER ENDOPLASMIC RETICULUM: ASSOCIATION WITH DRUG-METABOLIZING ENZYMES

The cellular changes which lead to the increase of drug-metabolizing enzymes following drug administration are explained by correlating new biochemical data with previously reported electron microscopic and pharmacologic observations. Repeated administration of phenobarbital and several other drugs results in a quantitative increase of the smooth endoplasmic reticulum of the liver cell. The marked increase in drug-metabolizing enzymes is found to occur in this enlarged smooth membrane fraction of the endoplasmic reticulum.

CHEMOTHERAPY OF ARTHRITIS INDUCED IN RATS BY MYCOBACTERIAL ADJUVANT

Arthritis induced in rats by mycobacterial adjuvant has been used for the study of compounds of known value in the treatment of rheumatoid arthritis in man. The development of the arthritic syndrome in treated and control rats was followed by measuring the changes in foot thickness of both hind-feet with a micrometer. This method allowed the effect of anti-inflammatory compounds to be expressed quantitatively. Anti-inflammatory activity was readily observed in certain steroids, pyrazolidines, salicylates and sodium aurothiomalate. Chloroquine and hydroxychloroquine were inactive. The inhibition obtained by daily treatment with the steroid paramethasone disappeared when treatment was withdrawn.