The Extraction of Smooth Muscle Contractile and Noncontractile Proteins from the Rat Small Intestine: Measurement of Protein Synthesis and Effects of Ethanol Toxicity

Apolipoprotein A-IV (apoA-IV) synthesis rates were measured in vivo in rat enterocytes by immunoprecipitation after administration of [3H]leucine into in situ loops of jejunum and ileum. Basal apoA-IV synthesis rates (percent total protein synthesis) were significantly higher in jejunal enterocytes (2.05 +/- 0.54%) compared with ileal enterocytes (0.48 +/- 0.32%) from the same fasted animals. After an acute triglyceride bolus, significant and sustained elevations of apoA-IV synthesis rates were seen in both jejunal and ileal enterocytes with maximal effects noted at 4-6 h. Animals fed diets containing 30% wt/wt triglyceride as saturated (SF) or polyunsaturated (UF) fats for 6 wk had similarly increased rates of apoA-IV synthesis in jejunal enterocytes with both SF (3.73 +/- 0.83%) and UF (3.33 +/- 0.64%) but no change in ileal enterocytes. By contrast, animals consuming a fat-free diet for 3 wk had jejunal apoA-IV synthesis rates indistinguishable from basal values (2.40 +/- 0.45%). Translatable intestinal mRNA levels for pre-apoA-IV after triglyceride increased in parallel to synthesis rates with a 50% increase in jejunum and a 350% increase in ileum observed at 4-6 h. These results suggest that apoA-IV synthesis by rat small intestine increases in response to acute and chronic dietary triglyceride, is maintained in the absence of dietary triglyceride, and may be under pretranslational control.

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[125I]His-neurokinin A binds selectively to NK2 receptors of the B-type in rat small intestine smooth muscle membranes

European Journal of Pharmacology Molecular Pharmacology ◽

10.1016/0922-4106(92)90124-e ◽

1992 ◽

Vol 227 (2) ◽

pp. 163-171 ◽

Cited By ~ 3

Author(s):

Michael C.S. Brown ◽

Marco Biagi ◽

Anna R. Renzetti ◽

Paolo Rovero ◽

Marco Criscuoli ◽

...

Keyword(s):

Smooth Muscle ◽

Small Intestine ◽

Neurokinin A ◽

Rat Small Intestine

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The effects of ethylenediamine in the rat small intestine: a powerful relaxant of the muscularis

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y91-029 ◽

1991 ◽

Vol 69 (2) ◽

pp. 199-204 ◽

Cited By ~ 1

Author(s):

Allison McKay ◽

Anthony Krantis

Keyword(s):

Smooth Muscle ◽

Small Intestine ◽

Muscle Relaxant ◽

Direct Action ◽

Circular Muscle ◽

Rat Small Intestine ◽

Intestinal Musculature ◽

Direct Acting ◽

Smooth Muscle Relaxant ◽

Better Than

The pharmacology of ethylenediamine (EDA) actions in the rat small intestine was examined using isolated gut-bath preparations of proximal segments of the duodenum, jejunum, and ileum. EDA evoked concentration-dependent tetrodotoxin-insensitive relaxations of the intestine, evidently by direct action on the muscularis. Such actions were simultaneous on the longitudinal and circular muscle layers. Investigation of EDA actions on the circular muscle showed that EDA actions were unrelated to any intrinsic GABAergic mechanisms. Moreover, EDA interacted with muscle sites distinct from ATP, histamine, bradykinin, muscarinic, and adrenergic receptors. The ability of EDA to relax the intestinal musculature was generally greater than the smooth muscle relaxant papaverine and substantially better than nicotinic stimulation of the intrinsic inhibitory neurones. It would appear that EDA may be useful as a direct acting smooth muscle relaxant for the study of the physiology–pharmacology of the rodent small intestine.Key words: ethylenediamine, rat intestine, muscle relaxant, circular muscle.

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