Article date: December 1988
By: I.P. Hall, S.J. Hill in Volume 95, Issue 4, pages 1204-1212
Histamine and carbachol produced concentration‐related increases in the accumulation of 3Hinositol phosphates in slices of bovine tracheal smooth muscle.
Noradrenaline alone produced a small stimulation of 3H‐inositol phosphate accumulation which was inhibited by the α‐adrenoceptor antagonist phentolamine. In contrast, when noradrenaline (0.1 mm) was added simultaneously with histamine it significantly reduced the inositol phosphate response to high (≥0.1mm) concentrations of histamine. However, noradrenaline had no inhibitory effect on the carbachol‐induced inositol phosphate response.
The non‐selective β‐agonist isoprenaline (IC50 = 0.08 μm) and the β2‐selective agonist salbutamol (IC50 = 0.29 μm) both produced a dose‐related inhibition of the inositol phosphate response to 0.1 mM histamine. The inhibitory effect of salbutamol was antagonized by propranolol (KA = 2.4 × 109M−1) and the β2‐selective adrenoceptor antagonist ICI 118551 (KA = 1.7 × 109 M−1).
The accumulation of 3H‐inositol phosphates induced by histamine increased steadily over a 40 min period after an initial lag period of 3–4 min. Following the simultaneous addition of histamine and salbutamol there was a further delay of 3–4 min before the appearance of the inhibitory effect of salbutamol.
The effect of histamine on inositol phosphate accumulation was accompanied by a stimulation of [3H]‐inositol incorporation into membrane phospholipids which was reduced by the presence of salbutamol. However, when histamine was used to stimulate maximally [3H]‐inositol incorporation during the prelabelling period, salbutamol produced a marked inhibition of histamine‐stimulated 3H‐inositol phosphate accumulation under conditions in which there was no change in the level of incorporation.
Histamine and carbachol produced concentration‐related increases in the accumulation of 3Hinositol phosphates in slices of bovine tracheal smooth muscle.
Noradrenaline alone produced a small stimulation of 3H‐inositol phosphate accumulation which was inhibited by the α‐adrenoceptor antagonist phentolamine. In contrast, when noradrenaline (0.1 mm) was added simultaneously with histamine it significantly reduced the inositol phosphate response to high (≥0.1mm) concentrations of histamine. However, noradrenaline had no inhibitory effect on the carbachol‐induced inositol phosphate response.
The non‐selective β‐agonist isoprenaline (IC50 = 0.08 μm) and the β2‐selective agonist salbutamol (IC50 = 0.29 μm) both produced a dose‐related inhibition of the inositol phosphate response to 0.1 mM histamine. The inhibitory effect of salbutamol was antagonized by propranolol (KA = 2.4 × 109M−1) and the β2‐selective adrenoceptor antagonist ICI 118551 (KA = 1.7 × 109 M−1).
The accumulation of 3H‐inositol phosphates induced by histamine increased steadily over a 40 min period after an initial lag period of 3–4 min. Following the simultaneous addition of histamine and salbutamol there was a further delay of 3–4 min before the appearance of the inhibitory effect of salbutamol.
The effect of histamine on inositol phosphate accumulation was accompanied by a stimulation of [3H]‐inositol incorporation into membrane phospholipids which was reduced by the presence of salbutamol. However, when histamine was used to stimulate maximally [3H]‐inositol incorporation during the prelabelling period, salbutamol produced a marked inhibition of histamine‐stimulated 3H‐inositol phosphate accumulation under conditions in which there was no change in the level of incorporation.
DOI: 10.1111/j.1476-5381.1988.tb11757.x
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