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I Tyssebotn

Publications and source records attributed to I Tyssebotn.

At least 55 records · Page 3Linked to original sources
PubMed1981

Distribution of blood flow in the dog kidney. III. Local uptake of 10 mum and 15 mum microspheres during renal vasodilation and constriction.

Recent studies indicate that intrarenal distribution of blood flow measured with microspheres (Ms) during control conditions depends on Ms size. We therefore compared local flow in outer and middle cortex (C1 and C2) and inner cortex plus the medulla (C3M) using 10.5-12.0 and 13.9-15.0 mum Ms (Ms 10 and Ms 15). One pair of Ms 10 and Ms 15 was injected during control and a second pair at 80% increased or 50% decreased total renal vascular conductance (RVC), as induced by infusion of acetylcholine (Ach) and angiotensin II (Ang) or noradrenaline (NA). All zones participated in dilation and constriction, as indicated by both Ms sizes. Ms 15 underestimated C3M flow as compared to Ms 10, by 19% during control or Ang, and by 3% during Ach (P less than 0.02). The C3M flow fractions increased during Ach and decreased during Ang, whereas NA gave greatly variable results, on average no change. Renal Ms extraction averaged 97.0 +/- 3% for Ms 10, 98.6 +/- 2.4% (S.D.) for Ms 15. About 8% of Ms 10 and less than 1% of Ms 15 were located in peritubular capillaries in each cortical zone. Neither total Ms extraction nor zonal extraglomerular Ms fraction changed over the present RVC range. Thus, the Ms 10 to Ms 15 differences as well as the observed redistribution must be due to differences in local entry of Ms into the afferent arterioles. However, steric restriction of Ms at arteriolar inlets did not play a significant role. The measured redistribution of fractional flow could in part be due to skimming of Ms at arteriolar inlets along the interlobular arteries (i.l.a.), depending on the C3M flow fraction, Ms size and i.l.a. diameter. If the observed fractional flow redistributions were solely due to variable Ms skimming, Ms 15 underestimated C3M flow by 53%, Ms 10 by 43%, during Ang as compared to Ach. Although Ms 10 and Ms 15 may correctly indicate the direction of fractional glomerular flow redistribution, at least Ms 15 overestimates this phenomenon quantitatively.

Acetylcholine↗
PubMed1981

Distribution of blood flow in the dog kidney. IV. Reversed net inward postglomerular capillary flow in the cortex after blocking interlobular arteries by 50 mum microspheres.

Simultaneous measurement of glomerular flow by 15 mum microspheres (Ms) and postglomerular capillary flow by 125I-iodoantipyrine (I-Ap) suggest that about 10% of total RBF flow inward through the entire cortex in the postglomerular capillaries of the dog kidney. This flow fraction might be variable (Clausen et al. 1978, 1980) and perhaps even reversible. To test this possibility we injected 50 mum Ms into the renal artery in order to obstruct interlobular arteries and produce a selective reduction of outer cortical glomerular blood flow and postglomerular pressure. The 50 mum Ms reduced total RBF by 50%. In the outer cortex, postglomerular flow measured by I-Ap was significantly less reduced than glomerular flow as measured by 15 mum Ms: Whereas the inward flow fraction from inner cortex to the medulla was maintained, about 5% of RBF now drained from midcortex to outer cortex. This observation support the theory of a variable net postglomerular capillary flow of radial direction in the cortex of the dog kidney.

Animals↗
PubMed1980

Renal blood flow distribution during E. coli endotoxin shock in dog.

The effect of endotoxin on renal blood flow distribution was studied in anesthetized dogs. Renal blood flow was measured as hydrogen clearance by platinum electrodes placed in outer and in inner halves of cortex and by electromagnetic flowmeter. Intravenous injection of E. coli endotoxin, 3-5 mg/kg b. wt., promptly reduced arterial blood pressure (AP) and renal blood flow. After a transient increase for 45 min AP and renal blood flow declined to about 50% of the control 2 1/2-3 h after injection. The reduction in outer cortical blood flow (OCF) was not significantly different from the reduction in inner cortical blood flow (ICF). The hematocrit (Hct) increased from 40.1 +/- 3.8% to 54.6 +/- 8%, but mean renal vascular resistance did not change. Total plasma protein concentration was not significantly elevated. A marked local flow variability was observed in some periods during the phase of shock with declining AP and total renal blood flow at high Hct. Thus renal blood flow showed phasic changes, but the OCF/ICF ratio was not changed during endotoxin shock. Local blood flow instability was observed periodically at high Hct.

Animals↗
PubMed1980

Patchy, intermittent ischemia in renal cortex during tourniquet shock in dog.

UNLABELLED: The effect of bilateral hindlimb occlusion on the distribution of renal cortical blood flow was investigated in anesthetized dogs. Local blood flow in outer cortex (OCF) and in inner cortex (ICF) was measured by 6 platinum electrodes recording hydrogen gas clearance. Renal blood flow fell unsignificantly while hematocrit (Hct) rose from 37 to 47% during the 4 h tourniquet period. After the release of the tourniquets average arterial blood pressure fell to about 75% of control, whereas OCF and ICF were proportionately reduced towards 30--40% of control. Hct increased to 58%. Patchy, intermittent ischemia in outer and inner cortex was irregularly observed after release of the tourniquets when Hct had increased markedly, as previously found during dehydration and endotoxin shock. The sudden shifts in washouts rates from single electrodes were not accompanied by corresponding variations in total renal blood flow. Heparinization of alpha-receptor blocking did not suppress the appearance of abrupt flow changes in this period. However, sudden shifts in local flow were also seen shortly after application of the tourniquets, before Hct had increased, in this phase possibly induced by an increased renal nervous tone. IN CONCLUSION: OCF and ICF fell to the same degree during tourniquet shock. Patchy, intermittent ischemia was observed in the renal cortex, most frequently at high Hct, but also before Hct did rise.

Animals↗
PubMed1980

Distribution of blood flow in the dog kidney. II. Saturation rates of inert diffusible tracers versus uptake of 15 mu microspheres during vasodilation and vasoconstriction.

While 15 mu microspheres (Ms) in principle provide a measure of glomerular flow, uptake rate of inert diffusible tracers indicates "effective" or "nutrient" flow, i.e. essentially postglomerular capillary flow. Paired measurements of glomerular and postglomerular flow were made in tissue samples from outer, middle and inner cortex (C1, C2, C3) and medullary zones. After a control Ms injection, renal vascular conductance (RVC) was altered in one kidney whereupon a second Ms injection was made, immediately followed by infusion of the 125I-iodoantipyrine and tritiated water. RVC was increased maximally by i.a. infusion of acetylcholine with and without reduced renal arterial pressure, whereas moderate vasodilation was produced by lowering renal arterial or rising ureteral pressure. RVC was reduced by i.a. or i.v. infusion of angiotensin II. Within a mean RVC range of 50 to 180% of control the fractional distribution of zonal postglomerular flow remained unaltered, in agreement with previous results obtained from local H2 gas desaturation rate. Glomerular flow was about 20% higher in C1, equal in C2 and 40% lower in C3 as compared to postglomerular flow in control kidneys. This disparity nearly disappeared during maximal vasodilation and tended to increase during vasoconstriction. The results might suggest a variable net postglomerular effective flow in radial direction through the renal cortex. Alternatively, the fractional redistribution of Ms might reflect a variable degree of Ms skimming at the afferent arteriolar inlets along the interlobular arteries.

Acetylcholine↗
PubMed1980

Effect of high ambient pressure and oxygen tension on organ blood flow in the anesthetized rat.

Cardiac output (CO) and blood flow to major organs were investigated in pentobarbital-anesthetized rats using 85Sr- and 141Ce-labeled microspheres (MS) (15 +/- 1 microns (SD)) injected into the left ventricle. Since MS dissolved in dextran cannot be used in albino rats, the method was evaluated using MS dissolved in Ficoll-70. Two subsequent MS injections were administered to each rat at normal gas atmospheric pressure (Group 1). The results demonstrated homogeneous mixing of MS dissolved in Ficoll-70 and good reproducibility of hemodynamic measurements using ventricular injection. In three other series, control measurements were performed in each rat at a normal gas atmosphere and at atmospheric pressure, and in one of the following experimental situations: at 5.0 atmospheres absolute (ATA) of ambient pressure and normal O2 tension (PO2 - 0.2 ATA) (Group 2); at an ambient pressure of 5 ATA and high O2 tension (PO2 = 1.0 ATA) (Group 3); and at normal ambient pressure and high O2 tension (PO2 = 1.0 ATA) (Group 4). The inert gas was nitrogen. Cardiac output, heart rate, and mean arterial pressure did not change in any group. Renal blood flow fell by 15% (P less than 0.05) in all groups except in Group 1. Myocardial and cerebral blood flow increased by 30% (P less than 0.05) in groups 2 and 3. Blood flow in the diaphragm fell by 40% (P less than 0.001) in Group 4.

Animals↗
PubMed1979

Renal cortical blood flow distribution measured by hydrogen clearance during dopamine and acetylcholine infusion. Effect of electrode thickness and position in cortex.

Blood flow distribution in the renal cortex was investigated in control and during i.a. infusion of dopamine (DA) and acetylcholine (Ach) in dogs. Local blood flow in outer cortex (OCF) and in inner cortex (ICF) was measured by platinum electrodes detecting hydrogen washout rate in tissue. Mean cortical blood flow measured by hydrogen washout rate in the renal vein (CFV) was compared with renal arterial blood flow (RAF) measured by electromagnetic flowmeter. With electrodes of 0.05-0.2 mm diameter control blood flow rates in outer and inner cortex were 4.57 +/- (S.D.) 1.73 ml/min.g, and 4.35 +/- 0.57 ml/min.g, which is higher than found using 0.2-0.5 mm electrodes in this and previous studies. OCF and ICF increased proportionally during intraarterial infusion of DA or Ach. The increase in local blood flow per unit volume was about 20% less than the increase in RAF, most likely due to an increase in renal volume and a reduced vasodilatory response in the surrounding of some electrodes. CFV rose almost to the same degree as RAF, showing a diffusion equilibrium for hydrogen gas even at maximal flow rate. During vasoconstriction induced by high doses of DA, OCF and ICF fell proportionately. Thus, equal vascular responses in outer and inner cortex were observed during both vasodilator and vasoconstrictor infusion. This indicates that changes in sodium excretion with renal blood flow may not be associated with a redistribution of cortical peritubular blood flow.

Acetylcholine↗
PubMed1979

Distribution of blood flow in the dog kidney. I. Saturation rates for inert diffusible tracers, 125I-iodoantipyrine and tritiated water, versus uptake of microspheres under control conditions.

Disparate reports on intrarenal blood flow distribution prompted a direct comparison between microspheres (Ms) and inert diffusible tracers (DT). The "tissue sampling technique" for estimating local flow with DT (Kety) was adapted for the dog kidney, using 125I-iodoantipyrine (1-Ap) and tritiated water (THO). Ms (15 micron) were injected 2-3 min prior to 10-15 s DT infusion made during continuous 1 s arterial blood sampling. Tracers were measured in 7 to 20 samples from each of the following zones: Outer, middle and inner cortex (C1, C2, C3), outer and inner halves of outer medulla (OM1, OM2), and inner medulla (IM). I-Ap and THO gave closely similar flow distribution, and average total renal blood flow (RBF) of 3.90 and 3.78 as compared to 3.94 ml/min . g with Ms. Flow in C2 (ml/min . g) was similar with all tracers, and in per cent thereof average local flows were: C1 102, C3 70, OM1 34, OM2 12, and IM 2 with DT versus 117, 53, 12, 3, and 0 with Ms. Zonal flow fractions of total RBF obtained with DT were: C1 0.41, C2 0.33, and C3+medulla 0.26 versus 0.51, 0.33 and 0.16 with Ms. Thus, a Ms surplus in C1 relative to DT flow, representing 10% of total RBF, matched a Ms deficit in C3+medulla. This disparity might result from: (1) Failure of Ms to enter deep afferent arterioles in proportion to blood flow, (2) diffusion of DT from deep portions of the interlobular arteries, and/or (3) postglomerular inward flow of blood and DT.

Animals↗
PubMed1978

The diagnosis of iron deficiency by erythrocyte protoporphyrin and serum ferritin analyses.

Free erythrocyte protoporphyrin (FEP) and serum ferritin have been determined in 57 healthy children and in 25 children with varying degrees of iron deficiency. FEP was found to be inversely correlated to the concentration of hemoglobin (r = -0.80) as well as to serum ferritin (r=-0.64). Elevated FEP was found in children with hemoglobin less than 12.5 g/dl, or serum ferritin less than 8 microgram/l. In a group of apparently hematologically normal children between the age of 10--14 years (hemoglobin greater than 12.5 g/dl), a 2-month-trial of iron medication resulted in an increase in hemoglobin and ferritin, and a decrease in FEP, indicating suboptimal supply of iron for hemoglobin synthesis before iron medication. In a patient with iron deficiency (FEP 15.3 mumole/l, hemoglobin 5.2 g/dl), iron therapy was followed by a rapid fall in FEP before any changes in hemoglobin, serum iron transferrin saturation and ferritin could be detected. The rapid fall in FEP during start of treatment in iron deficiency makes FEP a sensitive biochemical parameter on iron homeostasis in iron deficiency anemia.

Adolescent↗
PubMed1977

The effect of indomethacin on renal blood flow distribution during hemorrhagic hypotension in dog.

The effect of indomethacin in hemorrhagic hypotension (HH) on total renal blood flow (RBF) and cortical flow distribution was studied in 9 pentobarbital anesthesized dogs. Local blood flow was measured as hydrogen clearance by 6 platinum electrodes in outer and inner cortex. RBF was recorded by electromagnetic flowmeter. Injection of indomethacin (3-5 mg/kg b.wt.) to inhibit prostaglandin synthesis, reduced renal blood flow only a few percent in control period. After the pretreatment with indomethacin, bleeding to mean arterial pressure 50 mmHg decreased RBF abruptly to 25% of control flow. Thus a renal vasoconstriction is observed both in early and late periods of bleeding in contrast to the initial vasodilation observed during the first half an hour of HH when prostaglandin formation was not blocked. Local blood flow in outer cortex decreased proportionally to flow in inner cortex during bleeding in both the indomethacin treated as in the untreated group, indicating an equal vasodilatory effect of prostaglandin in all parts of renal cortex during early periods of HH.

Animals↗
PubMed1977

Effect of dehydration on renal blood flow in dog.

The effect of dehydration on intrarenal blood flow was investigated in 11 dogs, using polarographic determination of H2-gas desaturation for measuring local blood flow in inner cortex (ICF) and outer cortex (OCF). Dehydration was induced by 48 h water deprivation +2-300 mg ethacrynic acid (EA) per os the day before the experiment. Compared to a control group (n=9) ICF was markedly reduced to 2.40 +/- 0.47 ml/min X g (control 3.23 +/- 0.64) whereas OCF 3.29 +/- 0.80 ml/min X g was nearly unchanged (control 3.59 +/- 0.85). The ratio OCF/ICF was increased to 1.37 (1.11). Further dehydration by hypertonic peritoneal dialysis for 3 h increased Hct to 60 +/- 4 and further reduced OCF and ICF, without significant change of the OCF/ICF-ratio. At Hct above 55 sudden and intermittent changes in local cortical blood flow were recorded randomly at individual electrode sites, showing ischemic periods lasting for 1 to 60 min. Such flow changes were observed in 13 of 14 expts. and were not accompanied by changes in RBF. It is concluded that moderate dehydration causes a greater reduction of ICF than of OCF. Severe dehydration gives in addition rise to patchy, intermittent ischemia in both cortical layers.

Animals↗
PubMed1975

Effect of vasoactive agents on the distribution of renal cortical blood flow in dogs.

The distribution of renal cortical blood flow was studied in 6 Nembutal anesthetized dogs during control periods and during infusions of adrenaline, noradrenaline, angiotensin and vasopressin. Local cortical blood flow was measured as H2 gas desaturation rate recorded polarographically by platinum electrodes in outer and inner cortex. The total renal blood flow (RBF) was measured by an electromagnetic flow meter. In the control period the outer cortical blood flow (OCF) and inner cortical blood flow (ICF) averaged 3.59 (+/- S.D. 0.85) ml/min - g and 3.23 (+/- S.D. 0.64) ml/min - g, respectively. Infusions of the various vasoactive agents caused essentially equal vascular responses. All agents caused increased local renal resistance and reduction of RBF whether given intravenously or intraarterially. The RBF could be lowered to 20-50% of initial control flow by increasing doses of vasoactive agents. OCF and ICF fell proportionately and almost to the same extent as RBF, or OCF fell slightly more than ICF. There was no evidence for patchy or zonal hypoperfusion in cortex caused by infusion of adrenaline, noradrenaline, angiotensin and vasopressin.

Angiotensin II↗