Relative Blood Flow to the Gastric Lesser

Curvature of the Dog

JoHN DELANEV, M.D., PH.D., and EUCE~E GRIM, PH.D.

T HE COMMONEST SITES Of peptic ulcers in the stomach are the lesser curvature o~' the pars media and the pytoric antrum. ~-a It has been

suggested that this characteristic location may be the consequence of a less abundant blood supply to the mucosa of these areas than to the remainder of stonmchS' a-~ Ivy e t aI . , 1 for example, state: "We believe it would be advisable to study the blood supply of the stomach more than it has been. It is quite possible that in the evohltionary development of a fundic mucosa [or the secretion of acid of high concentration, which requires a copious blood flow, a similar increase in blood flow for ade- quate protection was not provided to the lesser curvature, pyloric antrum, and the duodenal bulb." The anatomic basis for possible less-abundant supply to the lesser curvature has been described by Reeves.a He has shown that the mucosal arteries in this region arise directly from the left and right gastric arteries rather than from the submucosal plexuses. They are longer, narrower, more tortuous, and have fewer anastomotic connections than their counterparts elsewhere.

If a state of relative ischemia exists normally in the lesser curvature

and antrum, these areas should be particularly vulnerable to such cir- culatory disturbances as a reduction in total gastric blood flow, partial occlusion of the small arteries or veins, or a diversion of blood flow away from capillaries to arteriovenous shunts. In an earlier study, 7 we showed

that the antrum of the canine stomach under normal conditions is per- fused with only one-half as mucb blood per gin. of tissue as is the body

of the organ. The purpose of the present study was to compare tissue blood flow in the lesser curvature with that in the ren/ainder of the body under several experimental conditions in order to determine if this region also is more poorly per fused.

From the Departments of Surgery and Ph}siotogy, University of Minnesota, Minneapolis, Minn.

Supported by Grants from the U.S. Public Health Service (GM K3-359 and HE- 02098), the Minnesota Heart Association, and the Graduate School of the Unixersity of Minnesota.

New Sedes, VoL 10, No. 3, 1965 201

Delaney & Grim

M E T H O D S

The measurement of blood flow to different regions and tissues of an organ can be practically accomplished only by indirect methods. For this study, the radioactive potassium, K/~2 clearance technic originally suggested by Sapirstein, s has been used. Earlier studies 7 in this labora- tory have demonstrated that this technic provides a valid measure of both total gastric blood flow and its distr ibution to the several regions and tissues of the stomach wall.

Mongrel dogs were fasted for 18 hr. and then anesthetized with sodium pentobarbi ta l (30 mg./kg.). Approximate ly 50 txc. of K 4~" Ct in a t-cc. voIume were rapidly injected via an inlying catheter in the inferior vena tara . T h e dog was sacrificed 25-35 sec. later by rapid infusion of 100 cc. of saturated KC1 solution through the same catheter. T h e abdomen was then opened and the stomach removed. T w o small full-thickness samples (1-2 gm.) of gastric wall were taken from. the anterior and posterior

aspects of the body, and a similar sample was cut from tlm lesser curva- ture of the pars media. T h e approximate location of the samples in indi- cated in Fig. 1. Each specimen was dissected into mncosa, submucosa, and muscle-serosa. T h e tissue portions were weighed and then digested in concentrated nitric acid. The isotope conlent of each was determined by counting in a well-type gamma scintillation detector.

Five groups of dogs were studied: Group 1, 6 untreated animals; Group

Fig. 1. Approximate

202

location of 3 stomach tissue samples analyzed for radiopotassium.

American Journal of Digestive Diseases

Blood Flow 'to Sfomach

2, 5 ted 1 can of horse meat dog food 1 hr. before the exper iment ; G r o u p 3, 5 animals given in t ravenous his tamine diphosphate , 1/,g. base per min- ute-ki logram (body weight) for 20 rain.; G r o u p 4, 5 given in t ravenous epinephr ine , 1 lag. base per nt inute-ki logram (body weight) for 15 min. ; G r o u p o,r~ 4 given in t ravenous no rep ineph r ine bi tartrate, _9 txg" base per mi imte-ki logram (body weight) for 15 rain.

R E S U L T S AND D I S C U S S I O N

For each animal the radioact ivi ty (perfusion rate) of the tissue l!rom the lesser curva ture was expressed as a percetitage of the mean radio- activity (mean perfus ion rate) of the two tissue samples taken f rom the poster ior and anter ior aspects of the body of the s tomach of the same animal. T h e means of these percentages for the tissue layers of the gastric: w a l l in the 5 groups of exper imenta l animals are summarized in T a b l e 1.

In the control animals the blood flow to the three tissues of the lesser curva ture was not significantly different f rom the ftow to the comparab le tissues of the o ther por t ions of the body of the stomach. T h e same was true for the 4 groups of treated animals, with the except ion that after norep i lmphr ine the blood flow through the submucosa and muscularis of the lesser curva ture was somewhat greater than in the rest of the organ. Despite the variat ions in total gastric flow produced by the drugs, the distribtJtion of this flow to these two different regions of the body re- mained essentially the same. Under no condi t ion studied was the flow to the mucosa of the lesser curvature significantly di l lerent f rom that to the mucosa of the rest of the organ. Th i s may be espcciatly no tewor thy in the case of feeding and his tamine adminis t ra t ion; bo th s t imulate gastric secretion, and the latter is c o m m o n l y used for the exper imenta l p roduc t ion of ulcers in dogs.

T h e l.esutts of this investigation provide no support for the not ion

"I'AI~LE t, RELATIVE BLOOD FLOWS TO THE TISSUES OF THE LESSER CURVATURE "z'

Exper imenta l gro'L@!'

I 2 "; 4 5

Mucosa 105 118 108 117 t05 sub m u cosa 95 110 18{) 101 1 t 91~, Muscula~is log I15 t 14 125 136}

ePercemages of the mean flow to the remai~der of the body of the stomach. ')'See text. :{A significant difference at the ar'°/,,o level or less.

New Series, Vol. 10, No. 3, 1965 203

Delarley & Grim

t ha t the lesser cu rva tu r e is more suscept ib le to u lcer f o r m a t i o n because i t has a lower pe r fus ion ra te than the rest of the body of the s tomach. T h e resul ts do not , ol! course, obv ia t e the poss ib i l i ty of a vascular fac tor in the p r e d i s p o s i t i o n of the lesser cu rva tu r e to pep t i c u lcer fo rma t ion . For example , the long, to r tuous mueosa l a r te r ies of t i le lesser cu rva tu r e may be more subjec t to a n a t o m i c obs t ruc t i on , as sugges ted by Seirafi and R e i d :

Since the dog se ldom deve lops s p o n t a n e o u s gas t r ic ulcer , one mus t be cau t ious in a p p l y i n g the resul ts o b t a i n e d here to the h u n l a n subject , I t is wor th no t ing , however , tha t the vascu la r a n a t o m y of the s tomach is essent ia l ly iden t i ca l in the two species.

S U M M A R Y A N D C ( ) N C I ~ U S I O N S

B l o o d flow to the tissues of the gastr ic lesser cu rva tu r e has been com- p a r e d wi th the flow to the rest of the body of the can ine s tomach by means of the r a d i o p o t a s s i u m c learance me thod . U n d e r al l the c i rcum- stances examined , the lesser cu rva tu re h a d at least as g rea t a pe r fus ion ra te as the rest of the s tomach, T h e s e obse rva t ions l end no s u p p o r t to the suggest ion tha t u lcer loca l iza t ion on the lesser curve is due to a n o r m a l l y ex i s t ing re l a t ive i schemia in tha t area.

Department of Ph)~siolog), Universily of Minnesota

Medical School Minneapolis .14, M bm,

R E F E R E N C E S

1. IvY, A. C., Gl~oss;xl.~N, M. L., and BaC.gACH, W. H. Peptic Ulcer. Blakistou, Phila- delphia, 1950.

2. PALm, lEg, E. D, Clirdcal Gastr~)enterology (ed. 2). Hoeber, New York, 1963, 3. BC×:KUS, H. I,. Gastroenterology (ed. 2). Satmders, Philadelphia~ 1963. 4. PA1,MER, :E. 1),, and B/XaIANAN, 1). P. On the ischemic basis of "peptic" ulcer. I.

Historical definition of present status. Ann. Int. Med. 38:1187, 1953. 5. SZ.:JRAF1, R., and RJ.:m, L. C. The ~ascular component in the causal genesis of peptic

ulcer. S'u~gery 5I:233, 1962. 6. R~:~vl~.s, T. B. A study of the arteries supplying the stomach and dnodenum and

their relation to ulcer. Su~\g. Gynec. '6 ° Obst. 30:374, 1920. 7. DELANt:~', J. P., and Gm~, E. Canine gastric blo<~| flow mid its distrib~ltion. Am..[.

Physiol. In press. 8. SAP]ERSTEtN, L. A. Regional blood flow by fractional distribution of indicators.

:Ira. I. Physiol. 193:161, t958.

204 American JournM of Digestive Diseases