• What do you understand by the term “endothelium-dependent” vasodilation?  Explain.

An increase in blood flow stimulates endothelium-dependent vasodilation by increasing shear stress on the endothelium, both in conduit and resistance vessels.

• When we talk about the NOS enzyme, what is meant by “constitutive” and “inducible” enzymes and what are the pathological and physiological implications thereof?

Constitutive enzymes: they are always produced whether or not a suitable substrate is present and this affects the process by which the synthesis occur and it is always present in the organism in constant amounts .

inducible enzymes: only expressed under conditions in which it is clearly of adaptive value ( used for breaking down of things in the cell).

• Explain how NO contributes to the fatal pathology of septic shock.

The physiological production of NO is important for blood pressure regulation and blood flow distribution. A hyperproduction of NO by the inducible form of NO synthase (iNOS) may contribute to the hypotension, cardio depression and vascular hyporeactivity in septic shock. 

• Which autacoids’ mechanism of action depends on effects on the guanylyl cyclase-cGMP system?

Nitric oxide.

• NO may be toxic to the cell.  Which mechanisms are available to the body to counter this detrimental effect of NO?

Nitric oxide is a potent and rapid inducer of methemoglobinemia. Exposure to Nitric Oxide may result in changes of the pulmonary system.

• Name a way in which NO can act pro-inflammatory.  Give examples of where it will have advantages or disadvantages.

NO is considered as a pro-inflammatory mediator. It induces inflammation due to over production in abnormal circumstances. Advantages: NO inhibitors represents an important therapeutic advance in the management of inflammatory diseases. They are proved to be used for the treatment of of NO-induced inflammation. Disadvantages: due to impaired production of vasoconstriction, inflammation and tissue damage.

• In which possible neurological and psychiatric diseases is NO involved?

Autism spectrum disorder, schizoprenia, (may play a role in the development of it). Bipolar disease, migraine, epilepsy, addiction.