FLOW OF BLOOD IN MESENTERIC VESSELS 



H43 



Grodins, 180 to 190 ml per min from tissue averaging 

 370 g in weight (0.5 ml/ min g). 



The studies on pancreatic blood flow have not 

 generally supplied sufficient information to permit 

 calculation of the flows per unit organ weight; 

 hence comparison with the values of Burton-Opitz 

 and Sapirstein are difficult. Babkin & Starling (6) 

 perfused the superior pancreaticoduodenal artery 

 from a heart-lung preparation and collected the 

 venous outflow in dogs under morphine and chloralose 

 anesthesia. They did not separate the pancreas from 

 the duodenum. In one experiment they observed a 

 control flow of 100 ml per min and in another 30 

 to 40 ml per min. No animal or organ weights were 

 given. Gayet & Guillaume (52, 53) measured the 

 outflow from the superior pancreatic vein in dogs and 

 obtained resting values of 20 to 25 ml per min in 

 animals of unspecified weight. Bennett & Still (14) 

 placed a stromuhr in the superior pancreatico- 

 duodenal vein of dogs of 8 to 9-kg body wt. Various 

 anesthetic agents were used: sodium barbital, sodium 

 amytal, and chloralose. They separated the pancreas 

 from the duodenum and estimated that they were 

 measuring the drainage of about one-half of the 

 organ. The mean flow was 6.2 ml per min. This is of 

 the order of 0.5 to 0.6 ml per min per g of tissue. 



Grindley et al. (69) used a thermostromuhr to 

 measure splenic blood flow in unanesthetized dogs. 

 They obtained a mean value of 95 ml per min which 

 is 50 per cent higher than that observed by Burton- 

 Opitz. Ottis et al. (104) employed electromagnetic 

 flowmeters in dogs anesthetized with sodium pento- 

 barbital and observed flows of about 30 ml per min 

 in dogs of approximately the same weight. While 

 this is much lower than observed by Burton-Opitz, 

 it is in better agreement with the findings of Sapir- 

 stein. It is important to note that in expressing splenic 

 blood flows per unit weight of organ, care must be 

 exercised in the definition of the organ weight. 

 Burton-Opitz found the spleen of his etherized dogs 

 to weigh about 5 g per kg body wt. postmortem. As 

 is well known, the spleen in animals anesthetized 

 with pentobarbital weigh three to four times this, 

 and Burton-Opitz' value of 0.8 ml per min per g 

 would accordingly be reduced to 0.2 or 0.25 ml per 

 min per g. 



An attempt has been made to summarize all this 

 data and to choose mean values which it is hoped 

 approximate the situation in the intact dog; these 

 are shown in table 1 . 



table 1. Blood Flow Through Mesenteric Organs of a 

 15-kg Dog Having an Arterial Blood Pressure 

 of Approximately 130 mm Hg 



* Weight and flow in ether anesthesia. f Same in pento- 



barbital anesthesia. 



Individual Tissues 



Since the arterial supply and venous drainage of 

 any tissue of a complex organ is by way of thousands 

 of microscopic vessels, the usual direct methods 

 cannot be employed to measure tissue blood flow. 

 Instead, one must resort to methods based on the 

 Fick principle. 



Shore et al. (125), in a study of the secretion of 

 basic drugs by canine gastric mucosa, found that 

 the clearance rates of drugs having a pK of 5 or 

 greater were equal and maximal for all the drugs 

 tested. They concluded that this maximal value was 

 equal to the mucosal blood flow. By measurement of 

 the concentration of drug in the gastropyloric venous 

 blood, they further discovered that the maximal 

 clearance was about two-thirds of the total gastric 

 blood flow; that is, approximately two-thirds of the 

 total flow passed through the secreting portion of the 

 mucosa. Schanker et al. (116) determined the clear- 

 ance of one of the same drugs, aniline, by the rat 

 stomach to be 75 ml per hour. On the basis of Sapir- 

 stein's findings, the total gastric blood flow in rats 

 of the same size is 140 to 150 ml per hour. Thus, a 

 minimum of one-half the total flow passes through 

 the secreting mucosa. 



Two different techniques have been employed by 

 workers in this writer's laboratory to obtain a reason- 

 ably complete analysis of the distribution of blood 

 flow through the tissues of the canine small intestine. 

 Lindseth (95) employed glass microspheres of 12 /u 

 in diameter labeled with Na 24 in dogs anesthetized 

 with sodium pentobarbital. After the injection of a 

 small quantity of the spheres into an intestinal artery, 

 the segment supplied by that artery was removed 

 and separated into its component tissues: mucosa, 

 submucosa, muscularis, and mesentery. The frac- 

 tion of the injected spheres in each tissue was de- 



