E. Pósch

Effect of suramin (Bayer 205) on renal ornithine decarboxylase activity and polyamine concentrations in rats

Abstract After a single high dose (20 mg/100 g i.v.) of suramin ornithine decarboxylase activity was increased rapidly in the rat kidney. Enzyme kinetic measurements indicate that on the basis of K m values renal ornithine decarboxylases from control or suramin treated rats are indistinguishable. Renal nucleic acid and polyamine levels were also enhanced in response to suramin. Changes observed in this study are considered as biochemical signs of induced renal growth.

Role of histamine in the development of neurogenic inflammation of rat oral mucosa

The mechanism of development of neurogenic inflammatory reaction induced by the topical application of capsaicin was studied in the oral mucosa of rats with or without histamine antagonist pretreatment.The existence of a cholinergic component of the vasodilation was investigated using a muscarinic receptor antagonist.Results indicated that the neurogenic inflammatory increases in vascular permeability and blood flow are mediated in part by H1-receptors. H2-receptors and cholinergic pathways are apparently not activated in these processes.

Effect of denervation on the neurogenic inflammation of the rat mandibular mucosa

SummaryEffects of local exposure to capsaicin on the vascular permeability and blood flow were studied in the rat oral mucosa at days 2 and 14 after the unilateral transcection of the inferior alveolar nerve (IAN). The distribution of nerve fibers displaying substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactivity (IR) in the mandibular mucosa was also assessed.While the capsaicin-induced augmentation in vascular permeability was about 50% (P < 0.05) higher on the intact side (at both days 2 and 14) than on the denervated side, no difference in blood flow elevation was seen between the two sides. Transection of IAN caused only a slight reduction in the density of SP- and CGRP-IR fibers in the mucosa.It is concluded that in addition to the IAN fibers the mandibular mucosa examined also seems to be supplied by other sensory fibers. The presence of accessory trigeminal branches was also supported by immunohistochemical studies.

Circulatory effects of intraduodenal acidification in the rat.

SummaryThe effect of intraduodenal administration of 0.3 ml/100 g 0.1 N hydrochloric acid and of the i.v. injection of 0.3 U/100 g secretin on the regional circulation was investigated in rats with the radioactive microsphere method. Intraduodenal acid produced a threefold increase in duodenal blood flow, jejunal perfusion was doubled, the perfusion of pancreas increased significantly. There were no significant changes in cardiac output, renal, myocardial, gastric and ileal blood flow. Secretin administration was without effect on the circulation. The same hormone dose produced a tenfold increase in pancreas secretion but was without effect on bile output. It is concluded that in the rat low doses of secretin do not elicit mesenteric flow changes similar to those observed after duodenal acidification.ZusammenfassungEs wurde an Ratten die Wirkung der intraduodenalen Einführung von 0,3 ml/100 g 0,1 N Salzsäure und der intravenösen Injektion von 0,3 E/100 g Sekretin auf die regionale Blutströmung mit Hilfe der radioaktiven Mikrosphären-Methode untersucht. Die Säuerung des Duodenalinhalts verursachte eine Verdreifachung der Durchblutung im Duodenum und ihre Verdoppelung im Jejunum. Auch die Pankreasdurchblutung nahm signifikant zu. Das Herzminutenvolumen, die Blutströmung des Magens, Ileums, Myocards und der Niere hatten sich nicht signifikant verändert. Sekretinverabreichung führte zu keinen signifikanten Veränderungen der Hämodynamik und der Organdurchblutung. Die gleiche Hormondosis verursachte eine zehnfache Zunahme der Pankreassekretion. Daraus wird geschlossen, daß bei Ratten eine mäßige Sekretindosis keine ähnliche Veränderungen der Mesenterialdurchblutung verursacht als die Säuerung des Duodenalinhalts. Mesenteric blood flow increases after a meal [7, 9, 18, 20, 23] and the reaction may be elicited by the intraduodenal perfusion of digested food [12]. It was assumed that the intestinal hyperaemia is confined to the segment-containing food [12] and is produced by the presence of chyme in the lumen [13]. On the other hand, it was shown by various techniques that intraduodenal introduction of 0.1 N hydrochloric acid increases splanchnic blood flow [2, 3, 5]. In the dog, duodenal acidification increased both hepatic artery and portal venous flow [1] but the localisation of the intestinal hyperaemia is unknown.The mechanism of the splanchnic circulatory changes is not yet fully understood. Vasodilatory responses have been reported after administration of the intestinal hormones gastrin, secretin cholecystokinin or GIP [8, 16, 17, 21]. It was suggested that physiological intraduodenal stimuli may lead to the release of endogenous intestinal hormones in an amount sufficient to account for the observed changes in mesenteric blood flow [9, 16]. It seems, however, that the circulatory changes are not produced by the action of a single intestinal hormone [6]. In the present investigation the effects of intraduodenal acidification on the regional circulation are studied in the rat, and the results are compared with those observed after secretin administration.

Suramin stimulates renal growth in the rat

Suramin given to rats in a single high dose (20 mg/100 g i.v.) stimulated renal growth. Maximum changes are taking place after 6–9 days of treatment.

Renal blood flow during ureteral obstruction measured with133Xe wash out,86Rb uptake techniques and with an electromagnetic flowmeter

SummaryIn moderate mannitol diuresis in the dog the ratio RBF-86Rb uptake/RBF-electromagnetic flowmeter decreased during ureteral obstruction from 0.923–0.705. In the same animals the ratio RBF-133Xe wash-out/RBF-electromagnetic flowmeter increased from 0.932–1.365. With the rubidium technique a significant redistribution of intrarenal blood flow was observed. No similar flow changes were seen with the133Xe wash-out technique. The two methods do not measure during ureteral obstruction the true RBF. The change of86Rb uptake by the individual segments of renal tissue is not an unequivocal proof for the intrarenal redistribution of bloof flow, but this possibility cannot be definitely excluded.

Measurement of regional blood flow with sulfanilamide (4-amino benzene sulfonamide).

SummaryA new technique utilising sulfanilamide (4-amino benzene sulfonamide) as a diffusible indicator is described for the measurement of organ blood flows in the rat. After a bolus injection the indicator is rapidly distributed in the tissue water and in most organs its tissue-blood partition coefficient corresponds to the relative water content of the organ. Sulfanilamide is, however, rapidly secreted by the renal tubules and slowly acetylated in the liver. This difficulty can be eliminated by the introduction of appropriate partition coefficients. The organ blood flows estimated with sulfanilamide were in the same animals compared with flows obtained by the86Rbuptake and by the radioactive microsphere techniques, and a high correlation was found between the flow values obtained by the different methods [sulfanilamide-86Rb:r = 0.992; sulfanilamide-MS:r = 0.995]. The merits and disadvantages of the individual methods are discussed.

Regional blood flow and collateral circulation of the tongue in the dog studied by hydrogen polarography

Regional lingual blood flow was measured by hydrogen polarography under control conditions and after the subsequent ligation of pertinent arteries in dogs. The results indicate a nonhomogeneous blood supply for the tongue and the existence of a complex collateral circulation in the lingual areas studied.

The effect of haemorrhage on renal blood flow and intrarenal flow distribution

Bleeding of dogs to constant arterial pressure of 90 mm/g and 60 mmHg respectively decreased renal blood flow in proportion to pressure reduction. There was no evidence of autoregulation of renal blood flow or of selective renal vasoconstriction. With the radioactive microsphere technique a moderate shift of blood flow from the outer to the inner cortex was observed. In the renal 133Xe wash-out curves exponent 1(attributed to the elimination of the indicator from the cortex) was more reduced than exponents 2 and 3 (medulla). These findings may not indicate a redistribution of renal blood flow through resistance changes in specific parts of the renal vasculature but may represent the consequences of focal cortical ischaemia, most prominent in the outer cortex.

Effect of indomethacin on the bradykinin-induced vasodilation in the submandibular gland

SummaryEffects of the local infusion of bradykinin or isoproterenol were studied on the systemic blood pressure, blood flow, and vascular resistance of the submandibular gland before and after indomethacin treatment in cats. Both bradykinin and isoproterenol were shown to potently increase the glandular perfusion rate. The systemic arterial blood pressure fell by about 20% in response to indomethacin. The enhancement of blood flow by bradykinin or isoproterenol was not, however, affected by indomethacin treatment. The present results appear to suggest that the endogenous prostaglandins are not essentially involved in the development of responses produced by bradykinin or isoproterenol in the cat submandibular gland.