Gaseous Messenger Research Paper

1.1.1 General introduction of gaseous messengers

Small molecules of endogenous gases which involve in cellular signaling thereby exerting physiological functions are termed as gaseous messengers or gasotransmitters. Gasotransmitters are a class above the receptor based signaling molecules as they are easily permeable across membranes and directly modify their intracellular targets.1,2 Nitric oxide (NO), Carbon monoxide (CO) and Hydrogen sulfide (H2S) are the enzymatically produced gases with biological functions to maintain the cellular homeostasis.3

Nitric oxide was the first discovered gaseous messenger for its regulatory activity in the nervous system and further research led to its role in immune system and vascular system. The research

alone, but under normal cellular environment production of NO., NO2 and NO3 was validated. (Fig 1.2) The L-arginine substrate provides the nitrogen atom implies that NO. acts as an intermediate product in the production of NO2 and NO3. Conversion of NO. into nitrites and nitrates suggests the detection of NO2 and NO3 in order to have a clear picture of RNS.

1.1.4 Hydrogen sulfide

For hundreds of years, Hydrogen sulfide (H2S) has been known as a poisoning and toxic pollutant. But in the past decade, the opinion has changed from noxious gas to gasotransmitter. It is colorless and highly soluble in water and lipophilic solvents, thereby all allowing it to diffuse through cell membranes and intracellular organelles.19 scientific reports have claimed the presence of H2S as gasotransmitter due to its stimulatory and inhibitory effects on nerve cells, cardiovascular system, endocrine system.20 Additionally, its role in cardioprotection from ischemic reperfusion injury and dialation of blood vessels have highlighted the protective nature. The physiological effects of H2S are exerted at a very low concentration of 10-100

Figure 1.3 various H2S generating reactions catalyzed by enzymes in the reverse transsulfuration pathway (CBS and CGL) and the cysteine catabolic pathway (CAT/AAT and