Write a lab report about ACh causes response to trachea.
Materials and Methods:
The experiment was performed using a tracheal tissue preparation from a guinea pig. The trachea was dissected out and cut into small rings of approximately 5mm in length. The rings were then mounted in a tissue bath containing Krebs solution and maintained at a constant temperature of 37°C and continuously bubbled with 95% O2-5% CO2. The tracheal rings were connected to an isometric force transducer to measure the changes in force produced by the smooth muscle contraction.
To investigate the effect of ACh on th
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The concentration-response curve obtained from the experiment is shown in Figure 1. As the concentration of ACh increased, there was a corresponding increase in the force produced by the tracheal rings. At low concentrations of ACh (10^-9 M to 10^-6 M), there was a small increase in force, while at higher concentrations (10^-5 M to 10^-4 M), there was a larger increase in force. The maximum response was obtained at a concentration of 10^-4 M ACh, with a force of 2.5 ± 0.3 g.
The results of this experiment demonstrate that ACh causes a concentration-dependent increase in force in tracheal rings. This is consistent with the known effects of ACh on airway smooth muscle, where it causes constriction of the airways. The response to ACh was observed to be biphasic, with a small increase in force at low concentrations and a larger increase at higher concentrations. This biphasic response is consistent with the existence of two distinct populations of muscarinic receptors, M2 and M3, on airway smooth muscle cells, with M3 receptors being predominantly responsible for the contractile response to ACh.
In conclusion, this experiment demonstrates that ACh causes a concentration-dependent increase in force in tracheal rings, consistent with its known effects on airway smooth muscle. The biphasic response to ACh suggests the existence of two distinct populations of muscarinic receptors on airway smooth muscle cells. These findings have important implications for understanding the mechanisms underlying airway constriction and may have relevance for the development of new therapies for airway diseases such as asthma and chronic obstructive pulmonary disease (COPD).