Evaluation of solid-phase labels for gastric emptying studies in cats.
Development of appropriate radiolabeled diets for solid-phase gastric emptying studies in experimental animals is important for testing the effects of disease, drugs, surgical procedures and stress. This study evaluates the in vitro and in vivo stability of various radiolabels in commercially available dry, extruded and canned cat foods.


METHODS
Dry, extruded cat food was labeled with 99mTc-pertechnetate, 99mTc-sulfur colloid or 99mTc-disofenin. Canned cat food was labeled with 99mTc-Dowex resin beads, 99mTc-pertechnetate, 99mTc-sulfur colloid or 99mTc-disofenin. A sample of each labeled diet and 99mTc-sulfur colloid-labeled egg was digested in water, gastric juice, intestinal juice or gastric juice followed by intestinal juice. The samples were centrifuged and the activity in the samples counted before and after removal of the supernatant. Based on in vitro results, three labeled diets were fed to 10-12 cats for in vivo testing.


RESULTS
99mTc-Dowex beads had the best labeling efficiency in vitro, but were not stable in vivo, resulting in unacceptable levels of circulating 99mTc. Technetium-99m-disofenin labeling resulted in in vitro percent solid-phase retention of 92.5% and 89.5% in water and gastric juice, respectively, for dry food and 86% and 94.9% in water and gastric juice, respectively, for canned food.


CONCLUSIONS
Technetium-99m-disofenin is a suitable label for solidphase gastric emptying studies using commercially available cat foods.
Hoskinson
J J
JJ
Department of Clinical Sciences, Kansas State University, Manhattan 66506, USA.
Goggin
J M
JM
Butine
M D
MD
D000284:Administration, Oral; D000821:Animal Feed; D000818:Animals; D002415:Cats; D004064:Digestive System / Q000000981:diagnostic imaging / Q000378:metabolism; D005746:Gastric Emptying; D007098:Imino Acids / Q000008:administration & dosage* / Q000493:pharmacokinetics; D015609:Organotechnetium Compounds / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011877:Radionuclide Imaging; D012469:Salivary Glands / Q000378:metabolism; D013670:Sodium Pertechnetate Tc 99m / Q000008:administration & dosage* / Q000493:pharmacokinetics; D019785:Technetium Tc 99m Disofenin; D013671:Technetium Tc 99m Sulfur Colloid / Q000008:administration & dosage* / Q000493:pharmacokinetics; D013961:Thyroid Gland / Q000378:metabolism
D007098:Imino Acids; D015609:Organotechnetium Compounds; D013671:Technetium Tc 99m Sulfur Colloid; D013670:Sodium Pertechnetate Tc 99m; D019785:Technetium Tc 99m Disofenin