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Abstract

Objective

To better characterize the source of the large nonparietal secretory response to pentagastrin (PG) expressed in gastric contents of cannulated horses.

Animals

Adult cross-bred horses: 4 geldings and 1 mare.

Procedure

Horses were prepared by surgical insertion of a silastic gastric cannula from which gastric contents after feed was withheld could be continuously collected by gravity drainage. During experiments, the horses were lightly restrained in stocks, the gastric cannula was opened, and a catheter was inserted into a jugular vein. Over the next 5 hours, gastric contents were collected in 15-minute aliquots for which volume, pH, [Na+], and [K+] were measured. During the first hour, treatment was not administered. At the start of the second hour, either 0.5 mg of omeprazole (OME; dissolved in glycerol formal)/kg of body weight, or 0.9% NaCI (PSS) of comparable volume, was given IV at random as a bolus. At the start of the third hour, IV infusion of PG (6 µg/kg/h) was started and continued for the next 2 hours.

Results

The response to PG in the PSS-treated horses was similar to that previously seen-significant decrease in pH and increase in volume of gastric contents, and no change in [K+] and [Na+], but a modest volume-related increase in their respective outputs. After OME treatment, pH of the contents increased sharply and remained between 5 and 6 throughout PG infusion. Sodium concentration significantly increased after OME and virtually paralleled the pH response throughout the rest of the experiment; volume of gastric contents significantly increased in response to PG infusion and resulted in a significant increase in Na output. There was no change in K output in OME-treated animals.

Conclusions

PG induces a marked, nonparietal, secretory response into the gastric contents of cannulated horses. The volume and [Na+] of this response was maintained after pretreatment with OME, although the pH of the contents became basic, indicating that this nonparietal response is not mediated by an OME-sensitive proton pump. (Am J Vet Res 1996;57:1640–1644)

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate feline injection site-associated sarcoma (FISAS) and oral squamous cell carcinoma (FOSCC) cells in 3-D hydrogel-based cell cultures to determine chemosensitivity to carboplatin at concentrations comparable to those eluted from carboplatin-impregnated calcium sulfate hemihydrate (C-ICSH) beads.

SAMPLE

2 immortalized cell lines, each from a histologically confirmed primary FISAS and FOSCC.

PROCEDURES

Hydrogels (10% wt/vol) were formed via UV exposure from methacrylamide-functionalized gelatin dissolved in PBSS. For each cell line, approximately 100,000 cells were encapsulated per hydrogel. Three cell-seeded 3-D hydrogels were evaluated for each carboplatin concentration (0, 150, 300, 450, and 600 µM) across 3 experiments. Drug efficacy was assessed by luminescence assay 72 hours after treatment. Growth of tumor cells treated with 300 µM or 600 µM carboplatin was evaluated using live-cell morphology imaging and confocal microscopy at 3, 7, and 14 days after treatment.

RESULTS

Mean half-maximal inhibitory concentration (IC50) values for FISAS and FOSCC cells ranged from 123 to 171 µM and 155 to 190 µM, respectively, based on luminescence assay. Viability at 3, 7, and 14 days for both cell lines at 300 µM carboplatin was 50%, 25%, and 5% and at 600 µM carboplatin was 25%, 10%, and < 5%.

CLINICAL RELEVANCE

3-D hydrogel cell culture systems supported growth of feline tumor cells for determination of in vitro chemosensitivity. IC50s of each cell line were within the range of carboplatin concentrations eluted from C-ICSH beads. Cells from FISAS and FOSCC cell lines treated with carboplatin showed dose-dependent and time-dependent decreases in viability.

Open access
in American Journal of Veterinary Research