So we obtained results from a previously done experiment and they are not what I expected.
response was measured at varying concentrations of norepinephrine in tissue with endothelium present and one without endothelium.
Without endothelium a higher tissue response was observed, I am not sure why apart from possible greater expression of b1 receptors?
ACh was then added to a bath containing the conc of norepinephrine that produced maximal response. This was done with endothelium and without.
I observed 0 response for the tissue with endothelium, I understand that Ach bind muscarinic 3 receptors and stimulate Nitric oxide release and thus vasodilation. What I don't understand is how this completely inhibits norepinephrine from illicit even just a small effect??
Contrastingly, in the tissue without endothelium , ACh produced an increase in response to that of norepinephrine on its own. This I am struggling to explain, what receptor did ACh target in this case and how did it enhance sympathetic activity of norepinephrine??
Thanks in advance