mRNA expression and binding sites for alpha2-adrenergic receptor subtypes in muscle layers of the ileum and spiral colon of dairy cows

Ontsouka, Edgar C; Blum, Jürg W; Steiner, Adrian; Meylan, Mireille (2006). mRNA expression and binding sites for alpha2-adrenergic receptor subtypes in muscle layers of the ileum and spiral colon of dairy cows. American journal of veterinary research, 67(11), pp. 1883-9. Chicago, Ill.: American Veterinary Medical Association 10.2460/ajvr.67.11.1883

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OBJECTIVE: To measure maximum binding capacity (B(max)) and levels of mRNA expression for alpha(2)-adrenergic receptor (AR) subtypes in ileal and colonic muscle layers of healthy dairy cows. SAMPLE POPULATION: Ileal and colonic muscle specimens from 6 freshly slaughtered cows. PROCEDURES: Ileal and colonic muscle layers were obtained by scraping the mucosa and submucosa from full-thickness tissue specimens. Level of mRNA expression for alpha(2)-AR subtypes was measured by real-time reverse transcriptase-PCR analysis and expressed relative to the mean mRNA expression of glyceraldehyde phosphate dehydrogenase, ubiquitin, and 18S ribosomal RNA. Binding studies were performed with tritiated RX821002 ((3)H-RX821002) and subtype-selective ligands as competitors. RESULTS: mRNA expression for alpha(2AD)-, alpha(2B)-, and alpha(2C)-AR subtypes was similar in ileal and colonic muscle layers. The mRNA expression for alpha(2AD)-AR was significantly greater than that for alpha(2B)- and alpha(2C)-AR subtypes, representing 92%, 6%, and 2%, respectively, of the total mRNA. Binding competition of (3)H-RX821002 with BRL44408, imiloxan, and MK-912 was best fitted by a 1-site model. The B(max) of alpha(2AD)- and alpha(2C)-AR sub-types was greater than that of alpha(2B)-AR. The B(max) and level of mRNA expression were only correlated (r = 0.8) for alpha(2AD)-AR. Ratio of B(max) to mRNA expression for alpha(2C)-AR was similar to that for alpha(2B)-AR, but significantly greater than for alpha(2AD)-AR. CONCLUSIONS AND CLINICAL RELEVANCE: Subtypes of alpha(2)-AR in bovine intestinal muscle layers are represented by a mixture of alpha(2AD)- and alpha(2C)-ARs and of alpha(2B)-AR at a lower density. Information provided here may help in clarification of the role of AR subtypes in alpha(2)-adrenergic mechanisms regulating bovine intestinal motility.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Veterinary Physiology
05 Veterinary Medicine > Department of Clinical Veterinary Medicine (DKV) > Clinic for Ruminants

UniBE Contributor:

Ontsouka, Corneille Edgar; Blum, Jürg; Steiner, Adrian and Meylan, Mireille




American Veterinary Medical Association




Factscience Import

Date Deposited:

04 Oct 2013 14:45

Last Modified:

04 May 2014 23:13

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URI: (FactScience: 807)

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