Altered calcium-handling properties of jejunal smooth muscle from the nematode-infected rat.
We examined changes in contractility of jejunal longitudinal muscle from rats infected 8 days previously with the enteric parasite Nippostrongylus brasiliensis. In uninfected control rats, carbachol-induced contraction was maximal at 1 microM carbachol. In muscle from infected rats, there was no change in ED50 for carbachol, but contraction induced by 1 microM carbachol was increased greater than 75% over that in control rats. No significant differences were observed in muscarinic receptor binding characteristics in smooth muscle cells from control and infected rats when [3H]QNB was used as radioligand. Contraction induced by 5-hydroxytryptamine was also substantially greater in muscle from infected rats. In control rats, carbachol-induced contraction was largely independent of extracellular Ca2+, whereas in muscle from infected rats, withdrawing extracellular Ca2+ reduced contraction to below control levels. Furthermore, whereas adding nitrendipine in the presence of extracellular Ca2+ had no effect on carbachol-induced contraction in control rats, it significantly inhibited contraction in muscle from infected rats.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D066298:In Vitro Techniques; D007411:Intestinal Diseases, Parasitic / Q000378:metabolism / Q000503:physiopathology*; D007583:Jejunum / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000503:physiopathology; D009349:Nematode Infections / Q000378:metabolism / Q000503:physiopathology*; D009559:Nippostrongylus; D009568:Nitrendipine / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology
D011976:Receptors, Muscarinic; D012701:Serotonin; D011813:Quinuclidinyl Benzilate; D002217:Carbachol; D009568:Nitrendipine; D002118:Calcium