Anti-inflammatory properties of N-phenylanthranilic acid derivatives in relation to uncoupling of oxidative phosphorylation

The involvement of lactate and calcium as mediators of the electrical and mechanical responses of the myocardium to conditions of simulated ischaemia

1. Rat isolated and superfused atria were exposed to a lactate-containing solution simulating the composition of extracellular fluid during myocardial ischaemia (SI). 2. Atria subjected to SI showed a decreased adenosine 5'-triphosphate (ATP) content, a rise in diastolic tension, a diminished conduction velocity of action potentials and shortened refractory periods. All these changes were less pronounced during lactate-free SI. 3. Atria preloaded with calcium displayed exaggerated responses measured electrically and mechanically during exposure to SI, whereas atria previously depleted of calcium displayed diminished electrical and mechanical responses to SI. Neither calcium loading nor calcium depletion modified the SI-induced depletion of the atrial stores of ATP. 4. Sulphinpyrazone protected atria against all aspects of the response to SI, but failed to protect the muscle under conditions of lactate-free SI. It is concluded that during SI, sulphinpyrazone protects against a lactate-mediated inhibition of the glycolytic synthesis of ATP. 5. Flufenamate exaggerated all responses of the atria to SI. These deleterious actions were still observed during lactate-free SI. It is concluded that flufenamate inhibits the synthesis of ATP in the mitochondria.

Decrease in peritoneal mast cell count in rats with adjuvant arthritis. II. Inhibition by anti-inflammatory and immunosuppressive drugs

The following drugs were administered daily to adjuvant-injected rats: indomethacin, flufenamic acid, phenylbutazone, prednisolone, dexamethasone, methotrexate and 6-mercaptopurine. The effects on the decrease in the mast-cell count and histamine content of the peritoneal fluid were studied as well as the effect on the development of polyarthritis 14 days after adjuvant injection. At the doses tested, these drugs markedly inhibited changes in the parameters of peritoneal fluid. With the exception of flufenamic acid, the preventive effects on the decrease in the peritoneal mast-cell count paralleled the prevention of development of arthritic lesions. 6-Mercaptopurine administered daily for 5 consecutive days starting from day 0 was almost as effective as when it was given over the entire period (days 0 through 13). These results show that the decrease in the peritoneal mast-cell count is one of the symptoms of adjuvant disease in rats that can be used for the quantitative evaluation of antirheumatic drugs.

Decrease in peritoneal mast cell count in rats with adjuvant arthritis. I. Time course and interstrain difference

Adjuvant was injected into the left hind paw of Sprague-Dawley (SD) and Wistar rats. In SD rats a marked decrease in the mast-cell count and histamine content of the peritoneal fluid and a significant increase in the histamine content as well as the mast-cell count in the mesentery appeared between 1 and 2 weeks after adjuvant injection. This period approximately coincided with that of the development of secondary inflammatory lesions such as polyarthritis. The adjuvant-induced changes in the peritoneal fluid were more marked in SD than in Wistar rats, corresponding to more intense adjuvant arthritis in the SD strain. In Wistar rats a tendency towards an increase in the histamine content of the mesentery was observed from 2 weeks after adjuvant injection. Adjuvant injection did not have any significant effect on the histamine content of the caecum or the skin of either strain. These results show that adjuvant causes a redistribution of mast cells between the peritoneal fluid and the tissues surrounding the peritoneal cavity probably as a result of delayed hypersensitivity.

Inhibition of adjuvant arthritis by salbutamol and aminophylline

Salbutamol (3 mg/kg) and aminophylline (75 mg/kg) were administered s.c. to rats separately or in combination after intradermal injection of adjuvant into the left hind paw. The paw volume was measured plethysmographically; tissue cyclic AMP content was determined by a protein binding assay following whole body microwave irradiation. The combination of salbutamol and aminophylline given daily significantly inhibited the swelling response in both the adjuvant-injected and the non-injected paws. This drug combination significantly increased the cyclic AMP levels in inflamed tissue of the adjuvant-injected hind paw and in lymphoid tissue such as the spleen and thymus. The combined treatment seems to have immunosuppressive as well as anti-inflammatory effects on adjuvant-induced arthritis.