Biomedical subjects
Publications and source records attributed to T Olin.
Ischemia of the kidney for 3 hours at a temperature of 16 to 18C will only impair renal function to a minimal degree measured by glomerular (51Cr ethylenediaminetetracetic acid) and tubular (125I hippuran) clearances. A newly developed device for surface cooling is described. The technique of clinical in situ surface cooling is recommended whenever an ischemia time for more than 10 minutes is expected.
An attempt to induce portal hypertension using Ameroid constrictors and shunt operations is described. 1 week after the application of the Ameroid constrictor around the portal trunk, it was completely occluded and portal venous pressure was elevated to a level about twice of normal range. Angiographically, splenorenal collaterals and collaterals overbridging the Ameroid constrictor were observed in all examined rats. However, esophageal varices could not be found in any rat. In the second series of the experiment, an end-to-side cavoportal shunt was created before the application of the Ameroid constrictor. This operation model was devised to increase the portal venous flow. At the same time this operation should inhibit the development of splenorenal collaterals and as expected collaterals to the superior vena cava system developed instead. However, they were not located in the esophageal wall but retroperitoneally.
A three-dimensional method to analyse the kinematics of the spine has been applied to four pigs with experimentally provoked scoliosis. The advantages and limitations of the method are discussed and some interesting facts concerning the provoked curves are emphasized.
Two different iodized oil emulsion have been intravascularly injected into rabbits, one with a particle size of 15 mum or more and one with a size of about 1 mum. The effects of the emulsions have been evaluated on the brain, the heart, the kidney, the liver and the circulation. The reactions to the small particle emulsion was minor, especially if administered slowly. The injection site was of critical importance. The safest place for injection was the superior mesenteric artery. If supplied directly to the brain or the heart the emulsions were often deleterious, particularly the coarse one.
The relation between ionic composition and cardiotoxicity of two dimers, iocarmate and iozomate, was investigated by selective injection into the left and right coronary arteries, Least toxic reactions developed at a sodium concentration of 263 to 315 mmol/l for sodium-meglumine iocarmate and 271 to 379 mmol/l for sodium-meglumine iozomate.
The abdominal arterial anatomy of the guinea-pig was investigated by angiography and dissection. Normally, a coeliacomesenteric trunk was found, although various forms transitional to the hepatolienogastric trunk were found. Multiple renal arteries were common in comparison to other laboratory animals and to man. A technique for selective catheterization of the abdominal arteries is described.
Lesions to the blood-brain barrier have been investigated in rabbits following constant or intermittent injections of sodium metrizoate into the internal carotid artery at different injection rates. Under certain experimental conditions the lesion to the blood-brain barrier was predominantly located to the brain area supplied by the contralateral carotid artery or the vertebral arteries. It is shown by serial angiography that the application time was shorter within the vascular territory of the paradoxical lesion. The results may imply that a mixture of blood and contrast medium is more vulnerable to the blood-brain barrier than contrast medium alone.
The distribution of infused 86 Rb Cl between different organs was followed for 48 hours. When SRVCL was perfused 15 hours after the 86 Rb Cl infusion, there was a redistribution with loss of Rb from the kidneys and the thigh musculature and an increase in the Rb concentration in the liver and shoulder musculature.
The aim of the present study was to examine the influence of surgical trauma on renal blood flow (RBF) and renal funciotn. The renal vessels were catheterized in lightly anaesthetized rabbits and the dye-dilution technique was used to measure renal blood flow and cardiac output. The renal fraction of the cardiac output (RBF % CO), the total peripherauation of the glomerular and tubular function was made by measuring the extraction of EDTA and of Hippuran. A decrease in the cardiac output was accompanied by a diminution of renal blood flow. Renal blood flow was reduced, regardless of whether surgery or puncture of the kidney was performed, probably due to vasoconstriction in the kidney caused by an increase in sympathetic tonus or in the concentration of plasma catecholamines. Manipulation of the renal artery seemed to stimulate further vasoconstriction in the ipsilateral kidney by a direct effect. The glomerular and tubular function decreased initially, independently of surgical trauma, and it is therefore assumed that the initial renal vasoconstriction includes the afferent arterioles. Renal function was not greatly influenced by handling of the renal artery.
The impairment of renal circulation and function in connection with general anaesthesia and surgical trauma was investigated in 19 rabbits. The systemic circulation and the renal circulation were evaluated by a dye-dilution technique and glomerular and tubular function by measuring the extraction of 51-Cr-EDTA and 125-I-Hippuran. In Group I measurements were performed before and after manipulation of the left renal artery preceded by topical application of a local anaesthetic. In Groups II and III measurements were performed before and after i.v. injection of, respectively, 0.8 and 3.0 mg/kg body-weight phenoxybenzamine, and then after manipulation of the renal artery. Blockade of the alpha-adrenergic receptors with phenoxybenzamine was found to preserve the renal fraction of the cardiac output. The blockade prevented an initial reduction in the extraction of EDTA and Hippuran, previously ascribed to general anaesthesia, but did not prevent a diminution following surgical handling of the kidney and the renal artery. The local anaesthesia had no effect. It is concluded that general anaesthesia and surgical trauma cause an impairment of the renal circulation due to an increased concentration of plasma catecholamines.
The renal artery was occluded in rabbits for varying lengths of time with the aid of a balloon catheter. Before and after the period of ischaemia, renal blood flow was measured by a dye-dilution technique and the glomerular and tubular functions were evaluated by measuring the extractions of labelled EDTA and Hippuran. Prolongation of the period of continuous ischaemia from 15 to 60 minutes resulted in a progressive increase in the postocclusive hyperaemia, but in a reduction of the renal function. Compared with 30 minutes of continuous occlusion, 30 minutes of intermittent occlusion caused only slight hyperaemia, but the same degree of reduction in renal function. One day after 30 minutes or 60 minutes of ischaemia, renal blood flow was within the range of the normal flow. After 30 minutes of occlusion, renal function was re-established 7 days later, whereas after 60 minutes of ischaemia, function was still severely impaired 7 days later. Fourteen days after 60 minutes of occlusion, renal function was 50% or less of the normal. Juxtamedullary shunting has not been demonstrated in the present investigation. Metabolic changes and cellular damage remain as possible explanations of the postocclusive changes in renal blood flow and function.
After 1, 2, 4, 7, 14 and 21 days of ureteral occlusion, renal blood flow was measured on both sides by means of a dye-dilution method and the glomerular and tubular functions were evaluated by measuring the extraction of 51-Cr-EDTA and 125-I-Hippuran. The results showed an increase in the weight of the obstructed kidney parenchyma and indicated an incipient compensatory hypertrophy of the contralateral kidney after 14 days of occlusion. The blood flow to the occluded kidney was reduced on the first day after ligation and ranged in all experiments between 24% and 44% of the total renal blood flow, without correlation to the duration of stasis. The blood flow to the contralateral kidney was mostly above the average in the control group. A small glomerular and tubular extraction was noted in more than 50% of the ligated kidneys. The glomerular filtration rate and the clearance of Hippuran by the contralateral kidney were increased after one day of occlusion, but no relationship between the changes in renal function and the duration of ligation was revealed. It is concluded that ureteral ligation causes a decrease in the blood flow to the occluded kidney and an increase in that to the contralateral kidney. The function of the contralateral kidney increases initially, but thereafter only as a consequence of the compensatory hypertrophy which is evident around the 14th day post occlusion.
The superior mesenteric blood flow in the post-absorptive state was studied with a dye-dilution technique using indocyanine green in 37 patients with apparently normal small bowel function. All the patients except 2 had been, or were to be, treated because of malignant disease, mostly rectal carcinoma. The investigations were performed in connection with portography. The dye was injected into the superior mesenteric artery as a single injection during continuous sampling of blood from the superior mesenteric vein, catheterized through the reopened umbilical vein. The blood flow was calculated from the dye-dilution curves obtained with a modified Stewart-Hamilton formula. As recirculating dye appeared in the later part of the dye-dilution curves, the appearance of the recirculating dye was timed in 4 patients. The hepatic extraction of the amount of dye usually injected, 1.25 mg, was 60%. The superior mesenteric blood flow averaged 706 ml/min (397 ml/min/m-2 body surface) or 12% of the cardiac output. The appearance time, mean transit time, vascular resistance and vascular volume were also determined.
The superior mesenteric blood flow was studied with a dye-dilution technique after catheterization of the superior mesenteric artery and vein. The investigation was performed in connection with portography in 22 patients with apparently normal small bowel function. Intra-arterial injection of 5, 10 or 20 mug bradykinin was followed within one minute by an increase, on the average, of 114, 176 and 223% respectively, in the superior mesenteric blood flow. The blood flow was dose-dependent in this range. The estimated vascular resistance decreased by 52, 61 and 67%, respectively. The portal venous pressure was increased slightly after intra-arterial injection, but the pressure was unchanged after intra-portal injection. Intra-arterial injection of bradykinin causes a highly improved venous phase at superior mesenteric angiography. This may be due not only to the increased flow but to some extent also to increased capillary permeability produced by bradykinin. Intra-arterial injection of 0.125 and 0.250 IU of vasopressin decreased the superior mesenteric blood flow by 53 and 54%, respectively, within 3 minutes of the injection. The dye-dilution method used was not applicable to blood flow below a level of about 200 ml/min. Continuous infusion of 0.05 IU/min decreased the superior mesenteric blood flow by, on an average, 58%. The portal venous pressure was decreased by 25% after the intra-arterial injection, but no change in pressure was recorded after intra-portal administration. The clinical use of intra-arterial infusion of vasopressin during gastrointenstinal bleeding is discussed.
The superior mesenteric circulation was studied with a dye-dilution technique after catheterization of the superior mesenteric artery and vein during provoked dumping in 5 patients. Dumping was provoked by intrajejunal instillation of 150 ml 50% glucose. A marked increase of, on the average, 157% was recorded in the superior mesenteric blood flow within a few minutes of the installation of glucose. The maximal increase in the flow was, on the average, 223% and occurred about 40 minutes after provocation. The instillation of glucose was promptly followed by a reduction in vascular resistance of the superior mesenteric vessels by 63% which decreased further to a mean maximal reduction of 76% below the resting level. The increase in the ratio between the superior mesenteric blood flow and cardiac output from 12 to 27% following instillation of glucose further underlines the pronounced vasodilatation of the small intestine. Superior mesenteric angiography at different intervals after provocation of dumping showed that the increased superior mesenteric blood flow is due to a local increase in the flow.
The superior mesenteric blood flow was studied with a dye-dilution technique after catheterization of the superior mesenteric artery and vein during the digestive phase after intake of a mixed meal (700 kcal). The material consisted of 5 patients. Within 5 minutes of the end of the meal the superior mesenteric blood flow, on the average, was increased by 60%. The largest increase was 113% and was noted one hour after the meal. The vascular resistance of the superior mesenteric vessles had by then fallen to a mean value of 55% below the prefeed value. The portal venous pressure was only slightly increased. The cardiac output was increased in 2 but slightly decreased in the remaining 3 patients. The pulse rate, blood pressure and haemoglobin concentration were largely unchanged. The ratio of the superior mesenteric blood flow to the cardiac output increased from 12 to 22% during the digestive period. The findings suggest the occurrence of a redistribution of blood after a meal with an increase in the superior mesenteric blood flow.
After subcutaneous transposition of the spleen in rats a rapid development of portosystemic collaterals occurs. It is demonstrated that variations in types and extent of splenic resection and in location after transposition lead to differences in collateral development. It is shown that the hilus portion of the spleen is the most important part to preserve. Extraperitonealization leads to less collateral development than does transposition to the subcutis.