Effect of indomethacin on cyclic nucleotide metabolism and vascular reactivity in rats

The content and metabolism of cyclic nucleotides in the aorta as well as contractility were studied in rats given different doses of indometacin. High doses of the drug (5 mg/kg) favored an abrupt decrease in cAMP and cGMP levels in the aorta and did not essentially affect vascular response to electric stimulation. Low doses of indometacin (2 mg/kg), particularly when coupled with salt load, resulted in the decreased cAMP/cGMP ratio and in the potentiation of vasoconstrictor responses. It has been demonstrated that the reduced proportion of cAMP in cyclic nucleotide metabolism is related to the activation effect of indometacin on cAMP-phosphodiesterase activity. The role of the prostaglandin-cyclic nucleotide system in the vascular tone control is discussed.     

Dicloxacillin: its chemotherapeutic action and experimental kinetic characteristics]

Activity against 50 clinical staphylococcal strains, chemotherapeutic efficiency, absorption and distribution of dicloxacillin in animals were studied in comparison with oxacillin. It was found that dicloxacillin was superior to oxacillin with respect to a number of their properties. The antibiotic was characterized by a higher antistaphylococcal activity, especially with respect to methicillin resistant strains. It was more effective in treatment of staphylococcal pneumonia and septicopiemia of albino mice. The drug was better absorpted when used orally and was detected in the blood in therapeutic concentrations for long periods of time. The antibacterial titer of the blood serum after dicloxacillin administration was 4 times higher than that of oxacillin.     

Several pathogenetic factors of experimental "indomethacin" hypertension]

The content of cyclic nucleotides (cAMP and cGMP) in the blood plasma, urine and tissues, and also morphological changes of the vascular renal bed were studied in rats with arterial hypertension induced by chronic inhibition of prostaglandin synthesis. A considerable thickening of the wall of the interlobular and arcuate arteries with marked lumen narrowing occurred mainly on account of hypertrophy and the swelling of smooth muscle cells. At the same time there was a marked increase in the cGMP concentration, a decrease of cAMP level, and a reduction of the cAMP/cGMP coefficient in the biological fluids. It is suggested that the changed cyclic nucleotides metabolism is associated with organic and functional changes of the peripheral vascular bed underlying an increase of the total vascular resistance in arterial hypertension.     

Dynamics of carrageenin-induced inflammation after use of lithium oxybutyrate

Lithium hydroxybutyrate (200 mg/kg) has been shown to depress the development of carrageenan inflammation. Subcutaneous drug injection in chronic inflammation of the mucous membrane in the hamster cheek pouch restored the blood flow, checked dilatation of the blood vessels, decreased their permeability and prevented necrosis of the mucous membranes. Subcutaneous drug injection depressed all the signs of both phases of acute inflammatory reaction in the rat hind foot and promoted preservation of the hind foot function. Therefore, lithium hydroxybutyrate may be an effective preparation for the treatment of inflammation.     

Acclimation or stress symptom? An integrated study of intraspecific variation in the clonal plant Aechmea bromeliifolia,a widespread CAM tank‐bromeliad

The clonal tank-bromeliad Aechmea bromeliifolia (Rudge) Baker was found in four different habitats in a restinga (vegetation mosaic on sandy coastal plains), of south-eastern Brazil. These habitats (swamp forest, dry forest, dry shrubland and herbaceous marsh) lie within a few hundred metres of each other along a gradient extending inland from the coast, and differ markedly in terms of light and flood regime. We compared ramet morphology, leaf anatomy and physiology, and population parameters to examine the amplitude of trait variation of this widespread species in the studied restinga. This integrated approach allowed us to examine which variation conferred acclimation and which was merely a stress symptom. A . bromeliifolia showed site-specific differences in abundance, distribution, rosette size and shape, leaf anatomical arrangement and photochemical efficiency (potential quantum yield; F _v/ F _m) during the day. Most of the variation found seemed to be related to the interaction of light and flooding. The lowest number and size of ramets at the exposed, dry shrubland was matched by a marked leaf photoinhibition, which suggested poor acclimation to local levels of light intensity and limited water supply. In the other habitats, the morpho-physiological parameters measured suggested adequate foraging behaviour and site acclimation.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140 , 391-401.