Relaxation time Release agents

Relative viscosity Relaxation time Release agent... 

The mechanism by which organic nitrates relieve the pain of angina pectoris was not discovered until nitric oxide was identified as the agent which was responsible for vasodilation of arteries. It was known for many years that endothelial cells released a factor that resulted in vasodilation a factor appropriately called endothelial relaxing factor (EDRF). It was, however, some time before the factor was identified, probably because it turned out to be a gas - nitric oxide - which was totally unexpected. Nitric oxide is now known to be a very important messenger molecule involved in the regulation of many other systems. The mechanism by which it causes vasodilation is described in Chapter 13. 

Smith (1957) described cases of reactions to suxamethonium and other muscle relaxants, which occurred on the first exposure to these drugs, and therefore, could only be explained by direct histamine release. That many drugs or other chemicals can act as histamine releasers has been known for a long time (Paton 1957). The review by Paton (1957) included neuromuscular blocking drugs. However, the most relevant question which has not been answered so far is why should some patients react so adversely to those agents in the absence of evidence of allergy ... 

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