(The) effects of hypothermia on exocrine pancreatic and biliary secretion
A number of studies have been carried out on pancreatic exocrine and on biliary secretion over the years, but recently there has been an increase in these studies following the development of the highly purified secretory hormones such as secretin and pancreozymin (Cecekin, Vitrum). However there have been very few reports of such studies being carried out under hypothermic conditions.
The present study was carried out on 12 dogs under normothermic and hypothermic conditions. The dogs were anesthetized with nembutal.
Several authors have confirmed the fact that lowering of the temperature of blood perfusing through the liver is associated with an increased resistance to the flow of blood. The flow of bile also is dramatically decreased during the time of cooling although the composition of the bile does not appear to be greatly changed during hypothermia.
Also, according to the literature, there are two mechanisms which cause a reduction of flow of pancreatic juice during hypothermia. The first is a reduction in pancreatic blood flow, and the second is a direct supression of cellular activity in the pancrease during cooling, and have noted a reduction in hepatic
blood flow and in biliary secretion associated with temperature reduction. This environmen tal reduction of temperature is known to be associated with a decrease in enzymatic activity, particularly in the serum levels and secretion volume of amylase and lipase. Trypsin levels in the pancreatic juice remain constant.
The level of bicarbonate in pancreatic juice during hoypthermia varied from 38.8mEq/L to 53.5 mEQ/L.
Methods and Materials:
12 adult male and female dogs weighing 10 to 18 gks. were anesthetized with intravenous pentothal sodium(30 mg./kg.)
At larparotomy, the terminal portion of the main pancreatic duct was isolated, lighted with suture at the point of its entry into the duodenum, and cannulated with a polyethylene catheter. The catheter was secured using a ligature around the duct.
Then the cystic duct was ligated and the hepatic duct cannulated with a polyethylene catheter.
Arterial blood was withdrawn through the femoral artery and the femoral vein was used for the infusion of stimulants. (1 or 2u./kg. of secretin and pancreozymin were used).
At 20 minutes interval, an initial collection of pancreatic and hepatic bile secretion was made at normothermic levels as determined by rectal temperature 38-39℃. Similar samples were collected after reduction of body temperature 27-28℃.
Hypothermia was carried out by placing the animal an ice water bath about 30-60 minutes period.
During hypothermia a mechanical respirator was used to assist respiration through an endotracheal tube. On several occasions acetazolamide(diamox) was used 10 mg./kg.
The concentration of bicarbonate was determined by the standard Van slyke procedure; Chloride was determined by an Aminco-catlove chloride titrator(American Instrument Co.). The concentration of amylase, lipase and trypsin in the pancreatic juice was determined by the methods of Nelson, Cherry and Crandall and Anson, respectively. The Beckman model G pH meter was used for pH determination.
Results and Conclusions:
A. Pancreatic Juice:
a. Flow rate: Pancreatic flow rate was decreased with hypothermia with only two exceptions. Following the administration of the diamox the flow was greatly reduced.
b. Bicarbonate(HCO^^3-) in the hypothermic state was moderately elevated but became markedly reduced after intravenous infusion of diamox.
c. Chloride(CI^^-) was slightly decreased in hypothermia, and markedly elevated after diamox administration.
d. Sodium(Na**+) levels were approximately equal under normothermia, hypothermia, and the administration of diamox.
e. Potassium (K**+) was slightly increased following secretin stimulation under hypothermia.
B. Hepatic Bile:
a. The flow rate of bile was considerably lower in the hypothermic than the normothermic state. affect the flow of bile significantly, but diamox did not.
b. HCO^^3- was slightly elevated under hypothermia but was lowered by the administration of diamox.
c. CI**- was lowered considerably under hypothermia than normothermia, and a markedly increase value was noted following administration of diamox.
d. Na**+ was elevated after secertin stimulation under hypothermia.
e. K**+ was unremarkably elevated under the hypothermic state after secretin and pancreozymin stimulation.
C. Enzymes: Lipase, Amylase and Trypsin.
a. Lipase: The highest value was found after pancreozymin stimulation during normothermia, under hypothermia, the reduction in lipase after pancreozymin was marked, but when pancreozymin was give with secretin, the lipase decrease was even greater than with pancreozymine alone.
b. Amylase: Almost the same effect as that following lipase was noted. Also a remarkable recovery in amylase was seen after pancreozymin stimulation. Pancreozymin stimulation was followed by a more remarkable recovery than secretin stimulation.
c. Trypsin: less prominent elevation with secretin under the normothermic state, and more prominent by pancreozymin stimulation. A remarkable diminution was noted in hypothermia and following diamox.
D. Cholate levels were rather higher in hypothermia than in normothermia.
E. Bilirubin: About the same value was noted in both the normothermic and hypothermic states. Diamox administration was followed by remarkably low levels.
Because of this study, the author is able to emphasize several points:
Firstly, linear correlation and reciprocal relation of HCO^^3- to CI**-concentration exists under hypothermia.
Secondly, HCO^^3- concentration was elevated either in the pancreatic juice, or in the hepatic bile under hypothermia.
Thirdly, CI**- concentration was decreased in the pancreatic secretions and inversely elevated in bile under hypothermia.
Fourthly, HCO**3- in the pancreatic juice was greatly lowered, but CI**_ was markedly elevated when diamox was given intravenously under hypothermia.
Lastly, enzymes were greatly reduced under the hypothermia, particularly lipase and amylase, and were even more decreased following diamox. Na**+ and K**+ showed no particular changes under either normothermia or hypothermia.