An animal model for the study of arterial thrombosis.

1. Thrombus formation induced by electrical stimulation of the carotid artery was investigated in anesthetized rabbits and rats. Occlusive Grade III thrombi were produced consistently in 34 normal New Zealand rabbits and 58 untreated albino Wistar rats.

[Intestinal absorption of glucose in anesthetized rats. I. Standardization of a method for screening of oral hypoglycemic agents].

This paper presents a method for the screening of natural hypoglycaemic drugs that interfere with the intestinal absorption of glucose. Luminal perfusion of the small intestine (whole length) was carried out on 24 h fasted adult Wistar rats, anaesthetized with sodium pentobarbital. Two rubber Nelaton cannulae were introduced into the organ, the first at the proximal end of the duodenum, just after the pylorus and a second larger one near the ileo-cecal valve.

Do platelets migrate into inflammatory exudates?

Rat platelets and the corresponding rabbit IgG antibodies mixed in polyester sponges implanted under the skin of normal animals caused an enhanced 24-h inflammatory response and a significant increase of prostaglandins in the exudate. These experimental results contrast with those obtained for normal rats implanted with sponges containing only IgG anti-platelet antibodies. The present experiments show that circulating platelets were not concentrated at the inflamed site and can hardly be considered of importance in acute inflammation.

Failure to identify 'thrombocytolysin' (a spasmogenic factor released from platelets immunoreaction) with anaphylatoxin.

Horse platelets release an unidentified smooth muscle contracting substance after lysis by antiserum and complement. Since the active factor (thrombocytolysin) does not produce tachyphylactic response of the guinea-pig ileum it seems that it is not related to anaphylatoxins.

Preparation and biochemical properties of PGH3.

PGH3 was biosynthesised from all-cis-5,8,11,14,17-eicosapentaenoic acid (20:5 omega 3) by an acetone-pentane powder of ram seminal vesicles and its structure was confirmed by GLC-MS after its reduction to PGF 3 alpha. PGH3 was transformed by horse platelet microsomes to TXB3, and by aortic microsomes to delta 17-6-keto-PGF 1 alpha. The structures of these compounds were confirmed by GLC-MS.

The effect of prostacyclin (PGT2) on platelet behaviour. Thrombus formation in vivo and bleeding time.

Prostacyclin (PGI2) infused intravenously into anaesthetized rabbits inhibited electrically-induced thrombus formation in the carotid artery, increased bleeding time and inhibited ex vivo platelet aggregation induced by ADP or arachidonic acid. The increase in bleeding time and the inhibition of ex vivo platelet aggregation lasted for as long as the infusion of PGI2 was maintained but rapidly disappeared after infusion was stopped. Prostacyclin is a more potent inhibitor of platelet function, in vivo than prostaglandin E1 (PGE1) or prostaglandin D2 (PGD2).

Transformation of arachidonic acid and prostaglandin endoperoxides by the guinea pig heart. Formation of RCS and prostacyclin.

The metabolism of arachidonic acid (AA) was studied in perfused isolated hearts from guinea pigs. The coronary effluent was continuously bioassayed for prostaglandin-like substances (PLS) using the cascade technique of Vane. Injections of AA in doses between 1--50 microgram into the perfusion fluid prior to the heart produced vasodilatation of the coronary vascular bed followed by a contraction of the rat stomach strip (RSS), chick rectum (CR) and rat colon (RC) as well as relaxation of the bovine coronary artery (BCA).

Enzymatic preparation of prostaglandin endoperoxides.

A simple and reliable method is described for the preparation of the endoperoxide intermediates (PGG2 and PGH2) in the biosynthesis of prostaglandins. The endoperoxides are thermolabile and easily decomposed by water (t 1/2 congruent to 5 min at 37 degrees C). Because of this, special precautions must be taken to work at low temperature and to minimize contact with moisture.

Platelets, Arthus-type reactions and inflammatory mediators.

The release of inflammatory mediators and the appearance of necrohaemorrhagic lesions induced by subcutaneous implantation of sponges containing antiplatelet serum globulins were studied in control and thrombocyto-penic rats. In thrombocytopenic animals, antiplatelet globulins caused a greater release of prostaglanding-like material and 5-hydroxytryptamine as well as larger inflammatory lesions. Thus, platelet integrity is not necessary for the induction of lesions by antiplatelet globulins and the mediators in the sponge exudates must have originated from leucocytes or damaged tissues.

Platelets, acute inflammation and inflammatory mediators.

The anti-inflammatory activity of aspirin-like drugs could derive, at least in part, by inhibiting synthesis and release of prostaglandins or rabbit aorta-contracting substance from platelets. Indeed, aggregation of platelets and the consequent release of inflammatory mediators has been frequently evoked as a factor in the development of the inflammatory reaction. The participation of platelets in acute inflammation was tested in three types of trauma in rats rendered thrombocytopenic with anti-platelet serum.

Platelets, Arthus-type reactions and inflammatory mediators.

The release of inflammatory mediators and the appearance of necrohaemorrhagic lesions induced by subcutaneous implantation of sponges containing antiplatelet serum globulins were studied in control and thrombocytopenic rats. In thrombocytopenic animals, antiplatelet globulins caused a greater release of prostaglanding-like material and 5-hydroxytryptamine as well as larger inflammatory lesions. Thus, platelet integrity is not necessary for the induction of lesions by antiplatelet globulinrom leucocytes or damaged tissues.

Are platelets important in inflammation?

The participation of platelets in acute inflammation was tested by three different traumas in rats rendered thrombocytopenic with anti-platelet serum. Thrombocytopenic rats showed normal oedema response to carrageenin, anti-platelet serum and passive cutaneous anaphylaxis.

The use of the hamster stomach in vitro as an assay preparation for prostaglandins.

1. Hamster stomach strips in vitro are useful test preparations for the assay of prostaglandins E and F in the nanogram concentration range. Three-minute cycles can be used for long periods without spontaneous contractions or significant base-line instability.