Pharmacologic identification of putative D1 dopamine receptors in feline kidneys.

The presence of dopamine (DA) receptors in feline kidneys is a matter of contention. Radioligand binding and Western blotting studies were employed to determine whether DA receptors are present in feline kidneys. The pharmacologic profile of the selective D1-receptor antagonist [3H]-SCH 23390 was studied in renal cortical membrane preparations from cats by conducting saturation binding isotherm and competitive binding experiments. [3H]-SCH 23390 bound to feline renal cortical membranes in a manner consistent with labeling of a D1-like receptor. The binding profile revealed a single site D1-like or D1 receptor in the feline renal cortex with a Kd = 7.8 +/- 1.0 nmol/L and Bmax = 76.5 +/- 19.5 fmol/mg. Competitive binding studies for [3H]-SCH 23390 against unlabeled agonists yielded the following Ki values and rank order of competition: SKF38393 (Ki = 0.47 +/- 0.26 micro m) > fenoldopam (Ki = 3.12 +/- 1.1 micro m) > DA (Ki = 933.1 +/- 1.6 micro m). Competitive binding studies for [3H]-SCH-23390 against unlabeled antagonists yielded the following rank order of competition: SCH 23390 (Ki = 1.97 +/- 0.81 micro m) > spiperone (Ki = 3.79 +/- 0.79) > metoclopramide (Ki = 4.26 +/- 2.4 micro m). Western blot analysis with anti-DA D1 receptor antibodies detected a single band with Mr of 74 kDa corresponding to a D1 DA receptor. These results suggest that a putative D1-like or D1 receptor exists in feline kidneys different from those previously identified in rat, dog or human kidneys.

Evaluation of the survival prediction index as a model of risk stratification for clinical research in dogs admitted to intensive care units at four locations.

OBJECTIVE: To prospectively evaluate a survival prediction index (SPI) in dogs admitted to intensive care units (ICU) and to generate and test an improved SPI (ie, SPI2). SAMPLE POPULATION: Medical records of 624 critically ill dogs admitted to an ICU. PROCEDURE: Data were collected from dogs within 24 hours after admission to an ICU. Variables recorded reflected function of vital organ systems, severity of underlying physiologic derangement, and extent of physiologic reserve; outcome was defined as dogs that survived or did not survive until 30 days after admission to the ICU. Probabilities of survival were calculated, using an established model (SPI). We then performed another logistic regression analysis, thereby reestimating the variables to create the new SPI2. Cross-validation of the models obtained was performed by randomly assigning the total sample of 624 dogs into an estimation group of 499 dogs and validation group of 125 dogs. RESULTS: Testing of SPI resulted in an area under the curve (AUC) of 0.723. Testing of SPI2 revealed an AUC of 0.773. A backwards-elimination procedure was used to create a model containing fewer variables, and variables were sequentially eliminated. The AUC for the reduced model of SPI2 was 0.76, indicating little loss in predictive accuracy. CONCLUSIONS AND CLINICAL RELEVANCE: The new SPI2 objectively stratified clinical patients into groups according to severity of disease. This index could provide an important tool for clinical research.

Use of jugular venous blood, compared with mixed venous blood, for measurement of venous oxygenation indices in a porcine model of endotoxic shock.

OBJECTIVE: To evaluate the reliability of oxygen saturation and oxygen content values measured from jugular venous blood in estimating values measured from mixed venous blood during endotoxic shock. ANIMALS: 14 random-bred 10- to 15-kg Yorkshire pigs. PROCEDURE: 60 pairs of heparinized blood samples were simultaneously collected from the pulmonary artery and right jugular vein during an independent study, using a porcine model of endotoxic shock. Endotoxic shock was induced by infusion of Escherichia coli endotoxin. Eighteen of the sample pairs were obtained from pigs prior to infusion of endotoxin or from control pigs. Oxygen saturation and venous oxygen content were measured by direct oximetry. Analysis of bias and precision was used to compare jugular venous blood values with values obtained from mixed venous blood. Samples from endotoxemic pigs were subclassified on the basis of abnormal states of global oxygen imbalance associated with septic shock. RESULTS: Indices of venous oxygenation measured from jugular venous blood were an imprecise method of estimating values measured from mixed venous blood. There was no significant difference in bias between nonendotoxemic and endotoxemic pigs, regardless of abnormal hemodynamic states. CONCLUSION: Jugular venous blood oxygen saturation and oxygen content values should not be used to assess global oxygen transport during endotoxic shock.

Blood substitutes: oxygen-carrying acellular fluids.

Blood substitutes are acellular fluids that can transport and deliver oxygen to the tissues. The blood substitutes most likely to be available and effective for veterinary use are the hemoglobin-based oxygen carriers (HBOCs) containing modified human, mammalian, or recombinant hemoglobin. HBOCs can be stored at room temperature and do not require typing or crossmatching. Chemical modifications of hemoglobin affect its physiologic and pharmacologic properties and facilitate oxygen transport. Although many of the metabolic and toxicologic consequences of HBOC infusion are not fully understood, an approved product will likely be available in the near future.