Article date: September 1991
By: Paul Gupta, Anthony Markham, Rae M. Morgan, in Volume 104, Issue 1, pages 123-127
The contractile response of guinea‐pig isolated trachealis to KCl has been studied in the presence and absence of cartilage.
Dissection of cartilage from the trachealis resulted in both a rightward displacement of the concentration‐response curve to KCl (EC50 value: intact strip, 26.9 ± 3.7 mmn = 5; dissected strip, 38.7 ± 2.6 mmn = 5; P < 0.05), and a reduction in the contractile response to KCl (30 mm) observed in a nominally Ca2+‐free medium.
Removal of cartilage from the trachealis did not alter the responsiveness of the tissue to CaCl2 (2.5 mm) when added to K+depolarized tissues.
Muscle‐denuded cartilage rings were prepared by surgical removal of the trachealis muscle. Autoradiographic studies, and a direct comparison of Ca2+(2.5 mm) uptake with that of sorbitol (2.5 mm) showed that cartilage per se had a high capacity to accumulate Ca2+ions by a process which was resistant to iodoacetate (100 μm), diflunisal (100 μm) and boiling.
The uptake of 45Ca into isolated cartilage was unaltered by the addition of orthovanadate (500 μm), verapamil (10 μm), diltiazem (10 μm) or Bay K 8644 (10 μm), but was significantly reduced (P < 0.05) in the presence of LaCl3 (1–10 mm).
We conclude, like previous studies, that cartilage may supply a pool of Ca2+ions to airway smooth muscle during the generation of tension in a noninally Ca2+‐free medium, and that LaCl3 may provide an experimental tool to elucidate further the role of non‐muscle Ca2+‐depots in smooth muscle contraction.
The contractile response of guinea‐pig isolated trachealis to KCl has been studied in the presence and absence of cartilage.
Dissection of cartilage from the trachealis resulted in both a rightward displacement of the concentration‐response curve to KCl (EC50 value: intact strip, 26.9 ± 3.7 mmn = 5; dissected strip, 38.7 ± 2.6 mmn = 5; P < 0.05), and a reduction in the contractile response to KCl (30 mm) observed in a nominally Ca2+‐free medium.
Removal of cartilage from the trachealis did not alter the responsiveness of the tissue to CaCl2 (2.5 mm) when added to K+depolarized tissues.
Muscle‐denuded cartilage rings were prepared by surgical removal of the trachealis muscle. Autoradiographic studies, and a direct comparison of Ca2+(2.5 mm) uptake with that of sorbitol (2.5 mm) showed that cartilage per se had a high capacity to accumulate Ca2+ions by a process which was resistant to iodoacetate (100 μm), diflunisal (100 μm) and boiling.
The uptake of 45Ca into isolated cartilage was unaltered by the addition of orthovanadate (500 μm), verapamil (10 μm), diltiazem (10 μm) or Bay K 8644 (10 μm), but was significantly reduced (P < 0.05) in the presence of LaCl3 (1–10 mm).
We conclude, like previous studies, that cartilage may supply a pool of Ca2+ions to airway smooth muscle during the generation of tension in a noninally Ca2+‐free medium, and that LaCl3 may provide an experimental tool to elucidate further the role of non‐muscle Ca2+‐depots in smooth muscle contraction.
DOI: 10.1111/j.1476-5381.1991.tb12395.x
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