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Biomedical subjects

R W Schmidt

Publications and source records attributed to R W Schmidt.

15 recordsLinked to original sources
PubMed1976

Bicarbonate reabsorption in the dog with experimental renal disease.

Renal bicarbonate reabsorption (expressed per unit of glomerular filtration rate, GFR) has been reported to be diminished in uremic man and uremic rats. Both the increases in parathyroid hormone concentrations and in natriuretic forces have been considered to play a role in this change. The increased kaliuresis per nephron observed in chronic uremia could theoretically also contribute to inhibition of bicarbonate reabsorption. Despite the common use of normal dogs in studying bicarbonate reabsorption and of uremic dogs in studying alterations of renal function in disease, few studies of bicarbonate reabsorption in uremic dogs have been performed. In the present studies we have examined bicarbonate reabsorption in normal dogs and in dogs with experimental renal disease using a conventional bicarbonate titration technique. In unanesthetized normal dogs, the threshold for bicarbonaturia was 24.8 mEq/liter of GFR. A maximal reabsorptive rate (Tm/GFR) of 34.0 mEq/liter of GFR was obtained. In a second group of dogs, GFR was decreased to one-fifth normal. FENa was increased 16.9-fold over normal values: UKV/100 GFR and FEP were increased 5.8-fold and 10.9-fold, respectively. The threshold for bicarbonaturia in these dogs was increased to 30.5 mEq/liter of GFR and the maximal reabsorptive rate was increased to 41.2 mEq/liter of GFR. Thus, the capacity to reabsorb bicarbonate was increased despite the presence of high fractional excretion rates for sodium, potassium and phosphate. This increased reabsorptive capacity could not be accounted for by the effects of other known determinants of bicarbonate reabsorption.

Animals↗
PubMed1976

Alterations in gastric physiology caused by selective embolization and vasopressin infusion of the left gastric artery.

Alterations in gastric physiology caused by selective embolization and vasopressin infusion of the left gastric artery were evaluated in 29 dogs. Gastric acidity was not significantly altered following Gelfoam embolization but decreased sharply with vasopressin infusion. These results suggest that the segmental occlusion caused by Gelfoam embolization permits significant collateral blood flow to the gastric mucosa, while the arteriolar and capillary constriction caused by vasopressin effectively decreases mucosal blood flow. These findings are consistent with the clincal observation that embolization is more effective in controlling bleeding ulcers, while vasopressin infusion is more effective for controlling hemorrhagic gastritis.

Angiography↗
PubMed1975

Control of experimental traumatic renal hemorrhage by embolization with autogenous blood clot.

Hemorrhage from artificially produced renal lacerations was controlled by selective arterial embolization with either plain or Amicar-mixed autogenous blood clot in ten dogs. The laceration sites healed as renal scars. Despite the presence of scattered, small renal infarcts caused by the embolization, hypertension did not develop in any dog during the two-month follow-up. No long-term differences could be detected between kidneys embolized with plain or modified clot. Although it is recognized that dogs have a more active fibrinolytic system than humans, the results of this study suggest that selective arterial embolization is a feasible method for controlling renal hemorrhage.

Angiography↗
PubMed1975

An inhibitor of sodium transport in the urine of dogs with normal renal function.

The urine and serum of chronically uremic patients and dogs contain an inhibitor of sodium transport that reduces short-circuit current (SCC) in the toad bladder and produces natriuresis in the rat. The present studies represent an effort to determine whether the same inhibitor is detectable in urine of normal dogs maintained on a dosium intake varying from 3 to 258 meq/day. Observations were made with and without fludrocortisone. The same Sephadex G-25 gel filtration fraction previously shown to contain the "uremic" inhibitor was tested in both the isolated toad bladder and rat bioassay systems. The fraction from dogs maintained on 258 meq qodium plus 0.2 mg fludrocortisone/day consistently inhibited SCC in the toad bladder and induced a natriuresis in the rat (P less than 0.001). The fraction from dogs on the same sodium intake without fludrocortisone was also natriuretic (P less than 0.01) but did not inhibit SCC significantly. In contrast, the fraction from dogs fed 3 meq sodium with fludrocortisone or 91 meq sodium without fludrocortisone had no significant effect in either assay system. Thus, an inhibitor of sodium transport has been found in the urine of nonuremic dogs. Both the degree of natriuresis in the rat and the degree of inhibition of SCC in the toad bladder correlated with the state of sodium balance which ensued in the dog.

Animals↗
PubMedDate not supplied

Selective arterial infusion of vasoconstrictors for control of traumatic splenic hemorrhage.

The spleen of each of 20 mongrel dogs was traumatized by creating a wedge laceration, and selective arterial infusion was then performed with vasopressin in four dogs, pituitrin in eight, and epinephrine in eight. Infusion therapy with vasoconstrictors controlled the splenic hemorrhage in 19 of 20 dogs. The 15 dogs surviving the experimental period of four to eight weeks showed well-healed scars at the sites of lacerations. Three dogs had small contracted spleens as a result of massive infarction. The results of this experiment indicate that splenic hemorrhage in the experimental dogs can be controlled by selective infusion of pituitrin or vasopressin, but is more effectively controlled with epinephrine.

Animals↗
PubMedDate not supplied

Effects of experimental embolization of superior mesenteric artery branch on the intestine.

A primary mesenteric branch of the superior mesenteric artery was embolized with Amicar-mixed clots in seven dogs and with gelatin sponges in five dogs. All of the dogs embolized with Amicar-mixed clots survived the experimental period and no mesenteric damage was found with postmortem studies. Three of the five dogs embolized with gelatin sponges showed a local stricture within the embolized segment of intestine. Collateral blood supply to the strictured segment of bowel in these three dogs developed via arterial arcades, mural branches of the vasa recta and omental arteries.

Aminocaproates↗