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Biomedical subjects

L Rentzhog

Publications and source records attributed to L Rentzhog.

29 records · Page 2Linked to original sources
PubMed1976

The effect of digitalis on regional ischaemia of the rat small intestine.

Research in recent years has shown that under certain conditions digitalis has a strong vasoconstrictive effect in the splanchnic region. This may imply that in cases of mesenteric ischaemia, digitalization may inhibit a collateral circulation necessary for restoration of the intestinal function. In this investigation the effect of digitoxin on the exchange circulation of the small bowel mucosa was studied in rats with induced regional ischaemia of the intestine. On analysis 30 min after establishment of the ischaemia a statistically significant negative effect of digitoxin was observed.

Animals↗
PubMed1976

Effect of chemical sympathectomy (6-hydroxydopamine) on gastrointestinal propulsion after laparotomy. An experimental study in the rat.

The effect of chemical sympathectomy on gastric evacuation and small bowel propulsion 15 hours after a standardized laparotomy was evaluated. The animals were pre-treated with 50 mg/kg i. v. of 6-hydroxydopamine 15 or 48 hours or 150 mg/kg 48 hours before the evaluation of gastrontestinal propulsion. The treatment did not prevent the postoperative retardation. On the contrary 6-hydroxydopamine in itself seemed to retard gastrointestinal propulsion. In simultaneously adrenal demedullated rats no further retardation was produced by the laparotomy.

Abdomen↗
PubMed1976

Effect of adrenergic blockade on gastrointestinal propulsion after laparotomy. An experimental study in the rat.

The effects of alpha-adrenergic and beta-adrenergic blockade on gastric evacuation and small bowel propulsion 15 hours after standardized laparotomy were evaluated. No retardation of gastric evacuation after the laparotomy appeared when alpha-receptor blocking treatment with phenoxybenzamine was instituted. Beta-receptor blocking treatment with propranolol did not prevent the retardation of gastric evacuation after the laparotomy. The time of analysis, 15 hours after the laparotomy, seemed to coincide with the period of resumption of normal small bowel propulsion.

Abdomen↗
PubMed1976

Effects of sympatho-adrenal activity and pharmacological treatment on gastrointestinal propulsion in the early postoperative period. An experimental study in the laparotomized rat.

Gastric evacuation and small bowel propulsion were greatly retarded two hours after laparotomy in the rat. Adrenal demedullation, chemical sympathectomy with 6-hydroxydopamine or treatment with a cholinesterase inhibitor (Neostigmin), an alpha-receptor blocker (Dibenyline) or metoclopramide (Primperan) did not improve the gastric evacuation. Chemical sympathectomy or treatment with metoclopramide, however, significantly improved small bowel propulsion. A significant reflux of duodenal contents to the stomach was found in several animals treated with the cholinesterase inhibitor or subjected to adrenal demedullation.

Abdomen↗
PubMed1976

Heme compounds in the plasma in small bowel ischemia in the rat.

The early diagnosis of acute mesenteric occlusion presents a difficult problem in abdominal surgery. In a study on rats the relation between graded small bowel ischemia and the concentration of heme compounds in the plasma was investigated. The ischemia was produced by ligation of terminal vessels at the mesenteric margin of the intestine (mesenteric end arcades) or the superior mesenteric artery. Heme compounds were assayed by a benzidine method developed by Crossby et al. The concentration of heme compounds in the plasma was higher in animals with various grades of intestinal ischemia than in animals subjected to laparotomy alone. This increase was noted as early as 4 hours after induction of moderate and severe grade of ischemia. The results indicate that an increase in plasma concentration of heme compounds takes place at an early stage of moderate and severe small bowel ischemia following mesenteric vascular occlusion but not until after 48 hours in mild ischemia. The clinical value of this method has to be tested in a clinical study.

Animals↗
PubMed1976

Effect of adrenal demedullation on urinary excretion of catecholamines in thermal trauma in rats.

The urinary excretions of adrenaline and noradrenaline were determined before and after a moderate thermal trauma in rats with intact adrenal glands, after adrenal demedullation and after adrenalectomy with grafting of adrenal cortical tissue. The basal excretions of adrenaline were 0.28 mug, 0.06 mug and 0.04 mug/24 h/rat, respectively. In rats with intact adrenal glands the adrenaline excretion was greatly increased already in the first 24 hours after the burn. In both the demedullated and adrenalectomized rats only a very slight increase of the adrenaline excretion was noted, but this may indicate a slight reaction of the extramedullary chromaffin tissue to the trauma. The basal excretion of noradrenaline was not affected either by demedullation or adrenalectomy, indicating that it consisted mainly in noradrenaline released from peripheral sympathetic nerve endings. From the second day after the burn there was an increase in the noradrenaline excretion, of equal magnitude in all experimental groups, indicating an increased liberation of peripheral adrenergic transmittor substances.

Adrenal Cortex↗
PubMed1975

Synthesis of catecholamines in the eye after local injection of 3H-precursors.

The possibility that adrenaline may be synthesized locally in the eye was investigated in the rabbit and vervet monkey. L-tyrosine-3,5-3H, L-tyrosine (side-chain-2,3-3H) or L-3,4-dihydroxyphenylalanine (3H(G)) was injected into the anterior chamber or the vitreous. The animals were killed after 1/2 h up to 7 days in the tyrosine experiments and after 1 up to 24 h in the DOPA experiments. The synthesis of 3H-adrenaline, 3H-noradrenaline and 3H-dopamine was measured with a modified version of a double isotope technique for determination of catecholamines. No 3H-adrenaline was found. An attempt to stimulate the phenylethanolamine-N-methyltransferase activity with a glucocorticoid and to inhibit the metabolism of catecholamines with a monoaminoxidase inhibitor also failed to demonstrate 3H-adrenaline synthesis. 3H-noradrenaline was found in all experiments when 3H-DOPA had been given. The amounts were about 10 times higher after injection into the anterior chamber than after injection into the vitreous. 3H-dopamine was found in all except a few experiments after 3H-DOPA injection. The highest amounts were found after injection into the vitreous. In experiments with 3H-tyrosine we were unable to demonstrate any catecholamine synthesis. This prompts the question of whether tyrosine-hydroxylase may be absent in the eyes of certain animal species.

Animals↗
PubMed1975

Pharmacological effects on gastric emptying following laparotomy in the rat.

Alteration of the gastrointestinal motility following abdominal surgery is a well substantiated clinical observation. Clinical reports concerning the effect of drugs theoretically suitable for normalizing inhibited gastric emptying during the postoperative period have been conflicting, however. The effect of chlorpromazine, neostigmine and metoclopramide upon retarded gastric emptying following laparotomy was studied in experiments on rats. Metoclopramide (Primperan) considerably improved the emptying ability of the stomach as early as 24 hours after laparotomy. After 72 hours this effect was further accentuated. No improvement of postoperatively retarded motility resulted from treatment with chlorpromazine or with neostigmine during the first 3 postoperative days.

Animals↗
PubMed1975

Experimental ischaemia of the small intestine. Effect of antibiotic and antithrombotic drugs on the mucosal exchange circulation.

Factors of decisive importance for the fate of the intestine following circulatory occlusion incluse the bacterial flora of the intestine, intravascular thrombosis peripheral to the level of occlusion, and the capacity of the collateral circulation. Standardized ischaemia of the small intestine was produced in the rat by ligation of a given number of mesentric end arcades. The passive absorption of radioiodide from a defined, central loop within the ischaemic intestinal segment-as an expression of the exchange circulation of the intestinal mucosa-was determined 14 days after induction of the ischaemia. Different forms of treatment were studied. In Sprague-Dawley rats the effect of heparin, oxitetracycline (OCD) and a combination of these two drugs was examined both concerning the survival of the animals and with regard to the available exchange circulation in the mucosa of the ischaemic intestinal segment. The survival frequency was increased in all treatment groups. The exchange circulation in the ischaemic segment was improved significantly by ODC-treatment and by treatment with heparin and ODC combined. Treatment with heparin alone gave no improvement of the mucosal circulation.

Animals↗