| 1. |
- Holm-Rutili, Lena, et al.
(författare)
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Pentagastrin and gastric mucosal blood flow
- 1986
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 250:5 Pt 1, s. G575-G580
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pentagastrin on mucosal microcirculation was studied in rats by use of intravital microscopy. The superficial mucosal vessels were videorecorded for off-line analysis of red cell velocities (VRBC) and vessel diameters, from which blood flow (QRBC) was calculated. Resting mucosal blood flow calculated from single microvascular flow data, and vessel distribution was 40 ml X min-1 X 100 g-1. Pentagastrin infused intravenously in a dose of 20 micrograms X kg-1 X h-1 resulted in submaximal acid secretion (approximately 60%) and a significant increase in QRBC by 47 +/- 14%. When given in a dose of 96 micrograms X kg-1 X h-1 iv, it resulted in maximal acid secretion and an increase in QRBC by 36 +/- 14%. In another series of experiments the results of QRBC measurements during infusion of pentagastrin (20 micrograms X kg-1 X h-1 iv) were compared with those of aminopyrine (AP) clearance or laser-Doppler flowmetry (LDF) in the same animals. Gastric mucosal blood flow determined by [14C]AP clearance increased by 309 +/- 115%, whereas QRBC increased by 34 +/- 11%. When determined by LDF, blood flow increased by 41 +/- 22%, a value similar to the increase in QRBC (50 +/- 19%). Thus, the percent increase in blood flow during pentagastrin infusion estimated by AP clearance was considerably higher than that observed by either direct microvascular measurements or by LDF.
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| 2. |
- Holm-Rutili, Lena, et al.
(författare)
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Rat gastric mucosal microcirculation in vivo
- 1985
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 248:6 Pt 1, s. G741-G746
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Tidskriftsartikel (refereegranskat)abstract
- The superficial gastric mucosal microcirculation was observed microscopically by transillumination in the anesthetized rat. The vessels surrounding the gastric crypts were monitored on a television screen through a microscope and the pictures stored on a videotape for off-line analysis of red cell velocity (VRBC) and vessel diameter. From these measurements microvascular volume flows were calculated. VRBC reached steady values after 1-4 h (mean 2 h) and showed a regular pulsatile flow (4-7 cycles/min) in most experiments. Acid output was measured at regular intervals; 50% of the rats showed no spontaneous acid output, but the others secreted up to 100 mu eq/h. The microvessels in the superficial mucosa were classified into three orders according to their branching hierarchy and relative dimensions, and their distribution per unit mass was estimated. VRBC and volume flow were shown to decrease in the successive orders of the microvessels. Calculation of organ blood flow from microvascular flow data and vessel distribution gave values (21 ml.min-1.100 g tissue-1) that agree with earlier reported values. A higher flow velocity was detected in rats with spontaneous acid output than in those without, but there was a poor correlation between the magnitude of the acid output and VRBC. Pentagastrin (96 micrograms.kg-1.h-1) induced a significant increase in both blood flow and acid secretion. Results from this study indicate that this experimental model is potentially useful for studies of the correlation between acid secretion and mucosal blood flow.
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| 3. |
- Lebel, L, et al.
(författare)
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Increased lymphatic elimination of interstitial hyaluronan during E. coli sepsis in sheep.
- 1989
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 256:6 Pt 2, s. H1524-31
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Tidskriftsartikel (refereegranskat)abstract
- The effect of septicemia on the elimination of hyaluronan (HA) from the lung interstitium was investigated in awake sheep with chronic lung lymph and thoracic duct fistulas. The result was compared with that after elevation of left atrial pressure (LAP). Lymph was sampled before and after a 20-min infusion of Escherichia coli (10(9) bacteria/kg body wt.), after elevation of LAP, or both. Infusion of E. coli caused an increased flux of HA in lung lymph and thoracic duct lymph. After an elevation of LAP, the HA flux in lung lymph was increased to a comparable extent. In animals subjected to an increase in LAP and subsequently to infusion of E. coli, no additive effect on HA flux was seen. The weight-average molecular weight of HA in lung lymph was increased both after sepsis and after elevation of LAP. The findings show that sepsis and elevated transvascular hydrostatic pressure result in increased mobilization of HA from the interstitium. This might partly explain the increased HA concentrations in plasma in clinical sepsis and may also lead to a change in the characteristics of the interstitial matrix in this condition.
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| 4. |
- Rundquist, I, et al.
(författare)
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Sciatic nerve blood flow measured by laser Doppler flowmetry and [14C]iodoantipyrine.
- 1985
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 248:3 Pt 2, s. H311-317
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Tidskriftsartikel (refereegranskat)abstract
- Blood flow was examined in sciatic nerves of pentobarbital-anesthetized rats by means of laser Doppler flowmetry (LDF) and intravenous [14C]iodoantipyrine infusion. Continuous LDF signals demonstrated slow oscillations and acute, pressure-related changes in flow. The steady-state LDF signal was related linearly to nerve blood flow, as measured with [14C]iodoantipyrine, in intact nerves and nerves stripped of the epineurium. In 14 intact nerves, nerve blood flow averaged 0.27 +/- 0.03 (SE) ml X min-1 X g-1, whereas it averaged 0.13 +/- 0.01 in 5 stripped nerves. Autoradiographs of [3H]-nicotine-infused nerves and intra-arterial injection of 57Co-labeled microspheres demonstrated that flow was not uniform throughout the nerve cross section. The results indicate that LDF can be used to examine nerve blood flow in vivo, demonstrate a linear relation between the LDF signal and flow, and establish absolute values for blood flow in intact and stripped nerves of the anesthetized rat.
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| 5. |
- Ödman, Svante, et al.
(författare)
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Peripheral nerve as an osmometer : role of endoneurial capillaries in frog sciatic nerve.
- 1987
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 252:3 Pt 1, s. C335-41
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Tidskriftsartikel (refereegranskat)abstract
- The sciatic nerve of the frog was perfused in vivo with isotonic Ringer solution followed by Ringer made hypertonic by addition of sucrose or of NaCl. Nerve diameter and endoneurial hydrostatic pressure fell during hypertonic Ringer perfusion. Using a model that describes the elastic and osmotic properties of the nerve, sigma sLp, the product of the osmotic reflection coefficient at endoneurial capillaries for s equals sucrose or NaCl (which approximates 1), and of capillary hydraulic conductivity, was found to equal 73 X 10(-13) cm3 X s-1 X dyn-1. The nerve is elastic. It has a compliance K of 3.7 X 10(-5) cm2 X mmHg-1, corresponding to a modulus of elasticity E of the perineurium equal to 1.2 X 10(6) dyn X cm-2. The results indicate that the nerve behaves as an osmometer during vascular perfusion, due to the low permeability of endoneurial capillaries to small solutes such as NaCl and sucrose. A low capillary hydraulic conductivity limits bulk water flow between blood and nerve, and a low compliance limits nerve swelling and edema.
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