Studies on human synovial membrane in vitro. The metabolism of normal and rheumatoid synovia and the effect of hydrocortisone

Abstract

The effect of various substrates on the metabolism of normal and rheumatoid synovial tissues in vitro was investigated in the presence and absence of hydrocortisone. Rheumatoid synovial membrane was capable of glycogen synthesis or breakdown. The presence of hydrocortisone resulted in an increase in glycogenolysis or a diminution of glycogen synthesis where this occurred. Glucose utilization of synovial tissue is inhibited by hydrocortisone under both aerobic and anaerobic conditions. Rheumatoid synovial tissue utilized glucose 1-phosphate, glucose 6-phosphate and fructose l:6-diphosphate under aerobic conditions. The utilization of these substrates gave variable results in the presence of hydrocortisone, although the inhibitory action on [image] was unaffected. Aerobic and anaerobic lactic acid formation was inhibited in the presence of hydrocortisone. The effect on the normal and rheumatoid synovia of malate, fumarate, succinate, acetate, pyruvate and glucose was investigated. Malate, fumarate and succinate stimulated O2 uptake. None of these substrates affected the respiratory inhibition produced by hydrocortisone. The inhibitory effect of a standard hydrocortisone concentration, on [image] of rheumatoid synovial tissues of varying degrees of metabolic activity, was greatest in those tissues which had the highest rates of O2 uptake. Synovial homogenates showed only slight anaerobic acid production unless diphosphopyridine nucleotide was added. With optimum conditions for glycolysis, hydrocortisone showed no inhibitory action. Splenic homogenates showed significant inhibition of anaerobic acid production by hydrocortisone.