PubMed · 9225085
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A F Hofmann. 1997. Biliary secretion: future perspectives.. https://doi.org/10.1159/000201519
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PGE2 exerts potent diuretic and natriuretic effects on the kidney. This action is mediated in part by direct inhibition of collecting duct Na+ absorption via a Ca++-coupled mechanism. These studies examine the role the Ca++-coupled PGE-E EP1 receptor plays in mediating these effects of PGE2 on Na+ transport. Rabbit EP1 receptor cDNA was amplified from rabbit kidney RNA. Nuclease protection assays demonstrated highest expression of EP1 mRNA in kidney, followed by stomach, adrenal, and ileum. In situ hybridization, demonstrated renal expression of EP1 mRNA was exclusively over the collecting duct. In fura-2-loaded microperfused rabbit cortical collecting duct, EP1 active PGE analogs were 10-1, 000-fold more potent in raising intracellular Ca++ than EP2, EP3, or EP4-selective compounds. Two different EP1 antagonists, AH6809 and SC19220, completely blocked the PGE2-stimulated intracellular calcium increase. AH6809 also completely blocked the inhibitory effect of PGE2 on Na+ absorption in microperfused rabbit cortical collecting ducts. These studies suggest that EP1 receptor activation mediates PGE2-dependent inhibition of Na+ absorption in the collecting duct, thereby contributing to its natriuretic effects.
The responses of 83 Meishan gilts given azaperone (1.0 mg/kg) and ketamine (5 mg/kg) intramuscularly at one of four sites: the cervical muscles (20); the triceps muscle (m triceps brachii) (20); the middle gluteal muscle (m gluteus medius) (22); and the fascia lata muscle (m fascia lata) (21) were recorded. There were more reactions to the injection into the fascia lata muscle than to injections into the middle gluteal muscle and the triceps muscle (P = 0.024) and fewest after injections into the cervical muscles (P = 0.013). The injection site did not influence the time from injection to recumbency but there was least variability with the fascia lata muscle. The degree of sedation achieved, and the response to venous cannulation were similar in all four groups. There were no long-term complications (lameness or abscess formation) associated with the injections at any of the sites. In a second study with 68 pigs the same drug mixture was injected into the triceps muscle at either 6 to 8 degrees C (23), 19 to 22 degrees C (23) or 38.5 to 40.5 degrees C (22). There was no significant difference (P = 0.078) between the numbers of responses to the injections at each temperature. Mean time to recumbency was shortest with the injections at the highest temperature although the differences were not statistically significant (P = 0.498). The degree of sedation achieved, the response to venous cannulation and the incidence of complications were similar in all three groups.