| 1. |
- Holm-Rutili, Lena, et al.
(författare)
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Autoregulation of gastric blood flow and oxygen uptake
- 1981
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 241:2, s. G143-G149
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to determine whether the ability of the stomach to autoregulate blood flow and oxygen uptake is altered by sympathetic denervation. Blood flow, oxygen extraction, local arterial pressure, and venous pressure were continuously monitored in sympathetically innervated and denervated autoperfused dog stomach preparations. As perfusion pressure was reduced in increments from 120 to 20 mmHg in innervated preparations, blood flow and oxygen uptake decreased while oxygen extraction and vascular resistance increased. Reductions in perfusion pressure in denervated preparations resulted in a decrease in blood flow, oxygen uptake, and vascular resistance, whereas oxygen extraction increased. The ability of the stomach to regulate blood flow and oxygen uptake was significantly improved after denervation, i.e., vascular resistance decreased and oxygen uptake remained relatively constant when arterial pressure was reduced. Oxygen uptake in denervated stomachs was generally higher than that in innervated stomachs. Autoregulation of gastric blood flow therefore appears to be improved by denervation. The better autoregulation observed after denervation may result either from a reduction in sympathetic tone and/or the increase in gastric oxygen demand.
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| 2. |
- Holm-Rutili, Lena
(författare)
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Effects of omeprazole on gastric mucosal microcirculation and acid secretion in the rat
- 1987
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Ingår i: Gastroenterology. - 0016-5085 .- 1528-0012. ; 92:3, s. 716-723
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Tidskriftsartikel (refereegranskat)abstract
- Omeprazole, a potent long-acting inhibitor of gastric acid secretion that exerts its inhibitory action by direct blocking of the H+, K+-adenosine triphosphatase in the parietal cells, was either applied topically to the solution bathing the exposed mucosa of the test rats or administered intravenously as a bolus injection. The superficial mucosal vessels were monitored on a television screen through a microscope and videorecorded for off-line analysis of red cell velocities and vessel diameters, from which blood flow was calculated. Intravenous omeprazole (5 or 10 mumol/kg) totally abolished the basal secretion 15-25 min after injection, with a parallel decrease in blood flow of approximately 25% for both doses. Omeprazole, 5 mumol/kg, given intravenously to rats stimulated with pentagastrin (20 micrograms/kg X h) significantly inhibited the stimulated acid output, but the blood flow was not significantly decreased. Topical application of omeprazole (2.5 mM in 6 ml) significantly increased blood flow (approximately 15%) while in contact with the mucosa both in the resting and in the pentagastrin (20 micrograms/kg X h)-stimulated situations. However, 10-20 min after the application period, blood flow was restored to the values before application of omeprazole and the acid output was significantly decreased. The results indicate that omeprazole exerts only minor influences on the gastric mucosal microcirculation in spite of its potent acid-inhibitory effect.
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| 3. |
- Holm-Rutili, Lena
(författare)
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Effects of prostaglandin E1, E2 and 16,16-dimethyl-E2 on gastric mucosal microcirculation and basal acid output in the rat
- 1986
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 127:3, s. 313-321
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Tidskriftsartikel (refereegranskat)abstract
- The effects of prostaglandins E1 (PGE1), E2 (PGE2) and 16,16-dimethyl-E2 (16,16-dm-PGE2) on the gastric mucosal microcirculation and (spontaneous) acid output were studied in anaesthetized rats. The superficial mucosal vessels were monitored on a TV screen using a microscope, TV camera and videorecorder for off-line analysis of red cell velocities (VRBC) and vessel diameters, from which the blood flow (QRBC) was calculated. The prostaglandins were either applied topically to the solution bathing the exposed mucosa or administered intravenously as a continuous infusion. Topical application of PGE1 (0.5 or 5 micrograms ml-1), PGE2 (5 or 50 micrograms ml-1) or 16,16-dm-PGE2 (0.005, 0.05 or 0.5 microgram ml-1) increased VRBC dose-dependently without altering acid output, except for the highest dose of PGE2 (50 micrograms ml-1) which inhibited acid output. The latter occurred in spite of a seven- to eight-fold increase in VRBC. Mucus secretion (evidenced by an impaired resolution of the TV image) also increased during topical application of the prostaglandins especially at higher doses. Intravenous PGE1, PGE2 (2.0 micrograms kg-1 min-1) or 16,16-dm-PGE2 (0.02 microgram kg-1 min-1) caused an initial and transient (5-10 min) fall in systemic arterial blood pressure and a decrease in VRBC and acid output. Intravenous 16,16-dm-PGE2 in a dose which did not affect secretion or systemic arterial blood pressure (0.002 microgram kg-1 min-1) still significantly reduced VRBC. Thus, topically applied PGE1, PGE2 or 16,16-dm-PGE2 dose-dependently increase VRBC while intravenous administration of the same prostaglandins reduce VRBC.
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| 4. |
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Smith, S M, et al.
(författare)
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Role of neutrophils in hemorrhagic shock-induced gastric mucosal injury in the rat
- 1987
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Ingår i: Gastroenterology. - 0016-5085 .- 1528-0012. ; 93:3, s. 466-471
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Tidskriftsartikel (refereegranskat)abstract
- Gastric mucosal clearance of 51Cr-labeled red blood cells (51Cr-RBC) was measured in rats during a 30-min control period, a 30-min ischemic period (hemorrhage to 27 mmHg arterial pressure), and a 60-min reperfusion period (reinfusion of shed blood). In untreated (control) rats, a dramatic rise in the leakage of 51Cr-labeled red blood cells into the gastric lumen was observed during the reperfusion period. Treatment with neutrophil antiserum attenuated 51Cr-labeled red blood cell flux into the gastric lumen. Using the radioactive microsphere technique, neutrophil-depleted animals were shown to have higher blood flows in the ischemic period than the untreated rats. Bleeding of untreated rats to a mean arterial pressure of 40 mmHg resulted in blood flows that were not different from those in antiserum-treated rats bled to 27 mmHg and leakage of 51Cr-labeled red blood cells similar to that measured in antiserum-treated rats. The results of this study indicate that neutrophils play an important role in hemorrhagic shock-induced gastric bleeding.
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| 8. |
- Torrång, Ingrid, et al.
(författare)
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A probabilistic approach for evaluating a technique for an indirect monitoring of the capillary blood flow to the gastric parietal cells
- 1987
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Ingår i: Bulletin of Mathematical Biology. - 0092-8240 .- 1522-9602. ; 49:2, s. 171-185
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Tidskriftsartikel (refereegranskat)abstract
- The superficial capillary network of the gastric mucosa can be monitored for red blood cell velocity measurements by a microscopic technique. This network, however, reflects the blood flow in capillaries of more physiological interest, namely those passing by the acid-producing cells and emptying into the superficial network. It is, however, not possible to study these capillaries directly and therefore the problem is to determine in what way and to what degree blood flow measurements in the superficial network reflect the capillary flow of interest. A probabilistic approach where the movements of the red blood cells have been analysed, gives indications of determinable relations between observations on the superficial network flow and the flow passing the acid-producing cells.
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