Norepinephrine dose-response curve

Dose-response curves to norepinephrine in the presence of two different a-adrenoceptor-blocking drugs. The tension produced in isolated strips of cat spleen, a tissue rich in receptors, was measured in response to graded doses of norepinephrine. Left Tolazoline, a reversible blocker, shifted the curve to the right without decreasing the maximum response when present at concentrations of 10 and 20 l mol/L. Right Dibenamine, an analog of phenoxybenzamine and irreversible in its action, reduced the maximum response attainable... 

Figure 1 Competitive antagonism ofY1 receptors by AXC00232. Norepinephrine (10 Xm) was used to stimulate the formation ofcAMP in SK-N-MC cells, and this stimulation was inhibited by the addition of NPY. Pre-incubation of the cells with AXC00232 produced parallel right-ward shifts in the NPY dose-response curves. The Schild transformation of the data is shown in the inset. Schild analysis yielded a slope of 1.08 and a calculated AJ, of 10 nM.

Fig. 2. The modification of the dose-response curve to norepinephrine by different concentrations of PGE. ...

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