During the acute inflammatory response, there is a period called the transient phase where there is increased vascular permeability. what is considered the principal mediator of the immediate transient phase?

Chemical Mediators

                               When injury occur in any part of the body, some chemicals are released in response to acute inflammation from injured area. These chemicals then spread to uninjured area cause immediate transient i.e cause vasodilation, chemotaxis, emigration of neutrophils and increase vascular permeability. These chemicals are called as chemical mediators.  

Example of chemical mediators

                  Some chemicals that are released from injured cells during acute inflammation are listed below:

1. Histamine.  

                  A well-known chemical mediator so far identified is histamine. It is stored in mast cells, basophils, leukocyte and platelets. It causes vascular dilation and release in response to complement system and lysosomal proteins released from neutrophils.

2. Lysosomal compounds

                 These are positively charged proteins released from neutrophils. It activates complement system and cause vascular permeability.  

3. Prostaglandins

                          These are derived lipids consist of long-chain fatty acids derived from arachidonic acid by the action of cyclooxygenase isoenzymes. It is a family of naturally occurring cyclopentane conatin carboxylic acid of varying degree of unsaturation. These chemicals are potent mediators that cause increased blood flow, chemotaxis (chemical signals that summon white blood cells), and subsequent dysfunction of tissues and organs.  

4. Leukotrienes

                      These are also derivatives of arachidonic acid in neutrophils and possess vasoactive properties. slow reacting substance of anaphylaxis (SRS-A), involved in type I hypersensitivity, is a mixture of leukotrienes. 5-hydroxytryptamine (serotonin). This is present in high concentration in mast cells and platelets. It is a potent vasoconstrictor.

5. Lymphokines

                        These compounds posses  the property of vasoactive or chemotactic attributes.  

Plasma factors.

Plasma is composed of:

1. Enzymatic cascade systems complement

2. The kinins

3. Coagulation factors, and

4. Fibrinolytic system  

All these are interrelated and produce various inflammatory mediators.

6. Complement system

                          It is a cascade of enzymatic cascade composed of nine different protein complexes. In necrotic cells enzymes are released from dying cells that activate complement system. However, when infection occurs, and the formation of antigen-antibody complexes establishes it lead to the activation of complement system. Similarly, exogenous pyrogens also activate complement system.

i believe the answer is a or 1