| 51. |
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| 52. |
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| 53. |
- Holm, Lena, et al.
(författare)
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Histamine is not involved in pentagastrin-induced gastric mucosal vasodilation in the rat.
- 1994
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 266:1 Pt 1, s. G55-61
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Tidskriftsartikel (refereegranskat)abstract
- The effects of histamine and its role in the gastric mucosal vascular response to pentagastrin were studied in anesthetized rats. Blood flow was measured with laser-Doppler flowmetry (LDF) and with red blood cell velocity measurements in the superficial mucosal microcirculation. Acid secretion was determined by titration of the saline covering 0.8 cm2 of the fundic mucosa. Pentagastrin (40 micrograms.kg-1 x h-1 i.v. induced a blood flow increase (+40%), which was not significantly altered by ranitidine (H2-receptor antagonist, 2 mg/kg iv bolus), whereas the stimulated acid output was abolished. In experiments in which the H1-receptor antagonist pyrilamine (2.5 mg/kg i.v. bolus) was administered before pentagastrin stimulation, pentagastrin still increased blood flow by approximately 60%. Intravenous histamine (4 mg.kg-1 x h-1) induced a blood flow reduction in parallel with the reduction in blood pressure (vascular resistance unchanged). Even during intra-arterial (thoracic aorta) infusion of histamine (1 or 4 mg.kg-1 x h-1), gastric vascular resistance was unchanged. In animals pretreated with pyrilamine, histamine (4 mg.kg-1 x h-1 i.v.) left the gastric blood flow and blood pressure unchanged. These results indicate that the pentagastrin-induced increase in the rat gastric blood flow is not dependent on histamine.
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| 54. |
- Holm, Lena, et al.
(författare)
-
Influence of tactile stimulation of the rat gastric mucosa on blood flow and acid output.
- 1993
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 265:2 Pt 1, s. G303-9
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Tidskriftsartikel (refereegranskat)abstract
- The influence of tactile stimulation of the gastric mucosa (mimics the mechanical influence of the food bolus) on the gastric mucosal blood flow and acid output was studied in rats anesthetized with Inactin. Blood flow was measured with laser-Doppler flowmetry (LDF) with the probe positioned above the gastric mucosa, and acid secretion was measured at regular intervals by titration of the saline covering 0.8 cm2 of the mucosa. After gentle tactile stimulation (wiping with cotton tips) of the mucosa for 20 s, blood flow increased to approximately 250% of the control value and then returned to the control level 15 min later, whereas acid output was transiently reduced immediately after tactile stimulation. Pretreatment with lidocaine, methysergide, or hexamethonium did not change the results of tactile stimulation on the blood flow. After indomethacin (3 mg/kg i.v.) LDF was significantly reduced by 33% and the hyperemic response to tactile stimulation was almost abolished. This suggests that endogenously released prostaglandins, not evoked through activation of intramural reflexes that can be blocked by lidocaine, methysergide or hexamethonium, are responsible for the hyperemia seen after tactile stimulation of the gastric mucosa.
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| 55. |
- Holm, Lena, et al.
(författare)
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Role of prostaglandins in regulation of gastric mucosal blood flow and acid secretion.
- 1992
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 263:4 Pt 1, s. G446-51
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Tidskriftsartikel (refereegranskat)abstract
- The role of prostaglandins in the rat gastric mucosal vascular response to acid stimulation was studied. Blood flow was measured with laser-Doppler flowmetry (LDF) and with red blood cell velocity measurements in the superficial mucosa; acid secretion was determined by titration. Baseline acid output was calculated to be 0.026 +/- 0.011 mueq/min. Pentagastrin (20 and 40 micrograms.kg-1.h-1 iv) significantly increased acid output to 0.387 +/- 0.104 and 0.546 +/- 0.220 mueq/min and LDF to 119 +/- 10 and 132 +/- 13% of control, respectively. LDF was significantly reduced by 15% after indomethacin (3 mg/kg iv) and was not changed by pentagastrin, whereas acid secretion increased to similar levels as without indomethacin pretreatment. The H2-agonist impromidine (100 and 500 micrograms.kg-1.h-1 iv) induced a dose-dependent increase in acid secretion (0.178 +/- 0.068 and 0.330 +/- 0.072 mueq/min, respectively) while blood flow was unchanged. Despite a substantial blood flow reduction (-38%) by indomethacin, impromidine did not alter blood flow, and acid secretion was dose dependently increased to similar values as without indomethacin pretreatment. These results provide further evidence that there is not necessarily any correlation between blood flow and acid secretion and that the pentagastrin-induced blood flow increase depends on prostaglandin release.
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| 56. |
- 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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| 57. |
- 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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| 58. |
- 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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| 59. |
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| 60. |
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