One type of photochemical reaction is the dissociation of a molecule into two fragments. Since it is the electrons that provide the bonding forces that hold atoms together into molecules, if the distribution of electrons within a molecule changes drastically, the bonding forces may also change.
Trade names: IntropinÂ®, DopastatÂ®, RevimineÂ®. Mechanistic Class: sympathomimetic, dopaminergic and Î² 1 -adrenergic agonist. Therapeutic Class: vasopressor. Mechanism of action: Dopamine is a natural catecholamine neurotransmitter and is the biological precursor to norepinephrine.It increases heart rate, cardiac contractility and blood pressure by multiple mechanisms. Dopamine causes norepinephrine release from sympathetic nerve endings.echanism of action: Dopamine is a natural catecholamine neurotransmitter and is the biological precursor to norepinephrine. It increases heart rate, cardiac contractility and blood pressure by multiple mechanisms.
The Dopamine Pathways. Dopamine is the neurotransmitter used by the reward pathway (also called the mesolimbic pathway, which is closely linked with the mesocortical pathway). But there are two other important pathways in the brain that use dopamine: the nigrostriatal pathway and the tuberoinfundibular pathway.Generally, drugs that affect dopamine levels affect all three of these pathways.erotonin is another neurotransmitter affected by many drugs of abuse, including cocaine, amphetamines, LSD, and alcohol. Serotonin is made by neurons in the Raphe nuclei. These neurons reach and dump serotonin onto almost the entire brain, as well as the spinal cord.