Effects of intravenous ethanol on hepatic and pancreatic blood flow in dogs

Chronic alcohol intake increases the severity of pancreatitis induced by acute alcohol administration, hyperlipidemia and pancreatic duct obstruction in rats

BACKGROUND

The mechanism of alcoholic pancreatitis is still unknown. It is of special interest why only about 5% of all alcoholics develop an episode of pancreatitis. We evaluated the role of long-term alcohol intake in the pathogenesis of alcoholic pancreatitis in rats.

METHODS

To evaluate the effect of long-term alcohol intake, rats were fed either a Lieber-DeCarli control diet (CD) or a Lieber-DeCarli alcohol diet (AD) for 6 weeks. Then, rats were infused over 2 h with either Ringer's solution (CO) or ethanol (E). In additional animals, alcoholic pancreatitis was induced by ethanol combined with hyperlipidemia and temporary pancreatic duct obstruction (EFO). Controls received Ringer's solution combined with hyperlipidemia and temporary pancreatic duct obstruction (RFO). Intravital microscopy (pancreatic perfusion and leukocyte adhesion), alcohol concentrations, amylase, lipase, cholesterine and triglyceride levels in plasma, myeloperoxidase activity and histology were evaluated at different time intervals.

RESULTS

In those animals which received the Lieber-DeCarli control diet, capillary perfusion was reduced in the E group and further reduced in the EFO group as compared to the controls (CO, RFO; p < 0.01). Leukocyte adhesion was significantly increased in rats receiving E (p < 0.01), and was further increased in the combination group EFO (p < 0.01). EFO induced histologically evident acute pancreatitis. The additional administration of a long-term alcohol diet further increased microcirculatory disturbances and pancreatic injury significantly (EFO-AD > EFO-CD).

CONCLUSIONS

This study shows that alcoholic pancreatitis is induced by the combination of ethanol and individual cofactors. Chronic alcohol abuse intensifies these changes. Therefore, long-term alcohol intake seems to be a major factor in the pathogenesis of alcoholic pancreatitis.

Cigarette smoke enhances ethanol-induced pancreatic injury

Alcohol induces pancreatic ischemia, but the mechanisms promoting pancreatic inflammation are unclear. We investigated whether cigarette smoke inhalation is a cofactor in the development of ethanol-induced pancreatic injury. Cigarette smoke was administered to anesthetized rats alone or in combination with intravenous ethanol infusion. Control animals received either saline or ethanol alone. Pancreatic capillary blood flow and leukocyte-endothelium interaction in postcapillary venules were evaluated by intravital microscopy. Leukocyte sequestration was assessed by measurement of myeloperoxidase activity in pancreatic tissue, and pancreatic injury evaluated by histology. Ethanol decreased pancreatic blood flow progressively over 90 minutes (p < 0.001 vs. baseline), but neither leukocyte-endothelium interaction nor leukocyte sequestration was altered. Cigarette smoke alone reduced pancreatic blood flow temporarily (p < 0.01 vs. baseline) and increased leukocyte-endothelium interaction (roller p < 0.001, sticker p < 0.01 vs. baseline). Cigarette smoke potentiated the impairment of pancreatic capillary perfusion caused by ethanol, and both the number of rolling leukocytes and myeloperoxidase activity levels were increased compared to ethanol or nicotine administration alone (p < or = 0.05 and p < or = 0.01, respectively). This study demonstrates that ethanol induces pancreatic ischemia and that cigarette smoke leads to both temporary pancreatic ischemia and minimal leukocyte sequestration. Cigarette smoke potentiates the amount of pancreatic injury generated by ethanol alone. Smoking therefore seems to be a contributing factor in the development of alcohol-induced pancreatitis in the rat model.

Effect of ethanol on pancreatic interstitial pH and blood flow in cats with chronic pancreatitis

OBJECTIVE

The objective of this study was to investigate the effects of ethanol on pancreatic blood flow and interstitial pH in chronic pancreatitis.

BACKGROUND

Ethanol is known to contribute to the development of both acute and chronic pancreatitis. However, it is unclear how ethanol precipitates episodes of acute pancreatic inflammation in the setting of chronic pancreatitis. In a model of chronic pancreatitis in cats, it is known that pancreatic blood flow is abnormally low and decreases further after ethanol ingestion. Because it is possible that this reduction in blood flow might be damaging to the pancreas, we investigated the effects of ethanol on pancreatic interstitial pH, an index of pancreatic ischemia.

METHODS

In normal cats and cats with obstructive chronic pancreatitis, pancreatic blood flow and interstitial pH were measured using the hydrogen gas clearance technique and pH microelectrode, respectively.

RESULTS

In normal cats, intragastric, but not intravenous, ethanol reduced both pancreatic blood flow by 62% (p < 0.05) and interstitial pH (7.38 +/- 0.03 to 7.20 +/- 0.03, p < 0.05). In cats with chronic pancreatitis in which basal pancreatic blood flow was already only 60% of normal flow, both intragastric and intravenous ethanol decreased both pancreatic blood flow (intragastric, 40% decrease, p < 0.05; intravenous, 34% decrease, p < 0.05) and interstitial pH (intragastric, 7.24 +/- 0.04 to 7.08 +/- 0.04, p < 0.05; intravenous 7.20 +/- 0.08 to 7.07 +/- 0.07, p < 0.05).

CONCLUSIONS

This profound decrease in pH, lasting up to 2 hours after ethanol exposure in the chronic pancreatitis animals, suggests the possibility of ischemic cellular damage to the pancreas. These findings may explain the pathogenesis of bouts of acute pancreatic inflammation after ethanol ingestion in the setting of chronic disease.

An alternative to radioactive microsphere for measuring regional myocardial blood flow, Part 2: Laser-Doppler perfusion monitor

OBJECTIVE

To compare measurements of regional myocardial blood flow volume between microsphere measurement of regional flow (0.5- to 2- g tissue sampling) and a potential alternative measure, local flow (1 mm3) in the microcirculation measured by laser-Doppler perfusion monitor.

DESIGN

Prospective, randomized, controlled.

SETTING

University research laboratory.

PARTICIPANTS

Pigs.

INTERVENTIONS

After anesthetization, in 5 pigs (25 to 30 kg), the left anterior descending coronary artery was isolated and its resting flow measured by a perivascular-Doppler flowmeter. Left ventricular pressure and first time derivative of left ventricular pressure were measured. The laser-Doppler probe needle (type N) (Model ALF-21, Transonic Systems, Inc, Ithaca, NY) was inserted 2 to 3 mm into the wall of the left ventricle, parallel to the coronary artery. All 5 pigs were subjected to 0 (control), 50% , 75%, and 100% constriction of the left anterior coronary artery.

MEASUREMENTS AND MAIN RESULTS

Measurements by radio-active microspheres correlated poorly with those by laser-Doppler and extremely poorly with those by perivascular Doppler flowmeter. For percent change from baseline in the constricted arterial zone, radioactive measurements correlated well with those by laser-Doppler but not those by Doppler flowmeter. Also, radioactive measurements of percent change in flow in the circumflex (nonconstricted) zone and laser-Doppler measurements in the constricted arterial zone did not correlate well.

CONCLUSIONS

Laser-Doppler can be recommended for experimental research to monitor local flow. These measurements may relate to change in regional flow during normal perfusion and hypoperfusion. Before the laser-Doppler perfusion monitor can be used clinically, tissue trauma from the 0.55-mm needle needs to be evaluated.

Acute effects of ethanol and ethanol plus furosemide on pancreatic capillary blood flow in rats

The effects of intravenous ethanol and ethanol plus furosemide on pancreatic capillary blood flow (PCBF) were investigated using a laser-Doppler flowmeter. Forty Sprague-Dawley male rats were divided into 4 groups: (1) control, (2) 80% ethanol, (3) 80% ethanol plus furosemide, and (4) furosemide. Mean arterial blood pressure and heart rate were monitored. Levels of serum amylase, calcium, electrolytes, ethanol, and furosemide (groups 3 and 4) were measured, and samples of pancreatic tissue were obtained. The ethanol and furosemide levels were statistically different (p < 0.05). PCBF significantly decreased (p < 0.05) in group 2, increased (p < 0.05) in group 3, and did not differ (p > 0.05) between groups 1 and 4. Histopathologic analysis revealed swollen acini in group 2 and sparse focal necrosis without acinar swelling in group 3. The depressant effect of ethanol on PCBF may be the result of its direct action on pancreatic cells causing edema and capillary compression rather than on primary vascular control mechanisms that adjust blood flow. Furosemide counters this effect.

Effects of gastric inhibitory polypeptide and glucagon on portal venous and hepatic arterial flow in conscious dogs

Gastric inhibitory polypeptide (GIP) has considerable structural homology with glucagon, which is known to increase liver blood flow. We compared the effects of GIP on portal venous and hepatic arterial flow with those of glucagon in conscious dogs. Injection of GIP significantly increased portal venous flow in a dose-related manner (by 7%, 15%, and 46% at doses of 1, 100, and 500 pmol/kg, respectively). The increase in portal venous flow induced by GIP and glucagon was comparable; however, the increase in portal venous flow after GIP injection reached its peak significantly earlier than that after glucagon injection. Hepatic arterial flow decreased after GIP injection (by 17%, 21%, and 35% at doses of 1, 100, and 500 pmol/kg, respectively), whereas it was not altered by glucagon. Thus, GIP causes significant changes in both portal venous and hepatic arterial flow in conscious dogs. Although structurally related, GIP and glucagon may influence liver blood flow through different mechanisms.

Effects of synthetic human gastric inhibitory polypeptide on splanchnic circulation in dogs

Changes in blood flow in the celiac artery, superior mesenteric artery, and pancreas in response to an intravenous injection of synthetic human gastric inhibitory polypeptide (GIP) were determined simultaneously and continuously in anesthetized dogs, using a transit-time ultrasonic flowmeter and a laser-Doppler flowmeter. Injection of GIP significantly increased superior mesenteric arterial flow in a dose-related manner (by 9%, 43%, and 139% at 30 s after an injection at the doses of 3, 50, and 800 pmol/kg, respectively). In contrast, celiac arterial flow was not significantly altered by GIP at any of the three doses. Calculated vascular resistance in the superior mesenteric artery decreased after GIP infusion, whereas that in the celiac artery was not changed by GIP. Pancreatic blood flow decreased significantly after GIP injection at the doses of 50 and 800 pmol/kg (by 11% and 17%, respectively). Our data indicate that there is a substantial difference in the hemodynamic responses to GIP among splanchnic organs, and suggest that GIP acts specifically on the mesenteric vasculature.