Pathways

Perflutren, a diagnostic drug that is intended to be used for contrast enhancement during the indicated echocardiographic procedures, comprised of lipid-coated microspheres filled with octafluoropropane (OFP) gas. It provide contrast enhancement of the endocardial borders during echocardiography. The perflutren lipid microspheres exhibit lower acoustic impedance than blood and enhance the intrinsic backscatter of blood. Perflutren is comprised of gas-filled microspheres that are injected or infused into the body. When exposed to ultrasound waves, the microspheres resonate and "echo" strong signals back to the ultrasound machine. The difference in density between the gas-filled bubbles and the blood around them creates an increased level of contrast visible in the resulting ultrasound image. During echocardiography, activated Perflutren enhances images of the inner edges or borders of the heart, producing an improved image that may enable physicians to better diagnose patients.

Pergolide is a drug that is not metabolized by the human body as determined by current research and biotransformer analysis. Pergolide passes through the liver and is then excreted from the body mainly through the kidney.

The dopamine D2 receptor is a 7-transmembrane G-protein coupled receptor associated with Gi proteins. In lactotrophs, stimulation of dopamine D2 receptor causes inhibition of adenylyl cyclase, which decreases intracellular cAMP concentrations and blocks IP3-dependent release of Ca2+ from intracellular stores. Decreases in intracellular calcium levels may also be brought about via inhibition of calcium influx through voltage-gated calcium channels, rather than via inhibition of adenylyl cyclase. Additionally, receptor activation blocks phosphorylation of p42/p44 MAPK and decreases MAPK/ERK kinase phosphorylation. Inhibition of MAPK appears to be mediated by c-Raf and B-Raf-dependent inhibition of MAPK/ERK kinase. Dopamine-stimulated growth hormone release from the pituitary gland is mediated by a decrease in intracellular calcium influx through voltage-gated calcium channels rather than via adenylyl cyclase inhibition. Stimulation of dopamine D2 receptors in the nigrostriatal pathway leads to improvements in coordinated muscle activity in those with movement disorders.

Perindopril is angiotensin-converting enzyme (ACE) inhibitor for the conversion of angiotensin I into angiotensin II. Angiotensin II is a critical circulating peptide hormone that has powerful vasoconstrictive effects and increases blood pressure. Perindopril is used to treat hypertension, high blood pressure, congestive heart failure, and chronic renal failure as it decreases blood pressure. Perindopril is converted into perindoprilat through the liver after being ingested which travels in the blood to inhibit ACE which is from the lungs. Angiotensin has many vasoconstrictive effects by binding to angiotensin II type 1 receptor (AT1) in blood vessels, kidneys, hypothalamus, and posterior pituitary. In blood vessels, AT1 receptors cause vasoconstriction in the tunica media layer of smooth muscle surrounding blood vessels increasing blood pressure. Less angiotensin II that is circulating lowers the constriction of these blood vessels. AT1 receptors in the kidney are responsible for the production of aldosterone which increases salt and water retention which increases blood volume. Less angiotensin II reduces aldosterone production allowing water retention to not increase. AT1 receptors in the hypothalamus are on astrocytes which inhibit the excitatory amino acid transporter 3 from up-taking glutamate back into astrocytes. Glutamate is responsible for the activation of NMDA receptors on paraventricular nucleus neurons (PVN neurons) that lead to thirst sensation. Since angiotensin II levels are lowered, the inhibition of the uptake transporter is not limited decreasing the amount of glutamate activating NMDA on PVN neurons that make the individual crave drinking less. This lowers the blood volume as well. Lastly, the AT1 receptors on posterior pituitary gland are responsible for the release of vasopressin. Vasopressin is an anti-diuretic hormone that cases water reabsorption in the kidney as well as causing smooth muscle contraction in blood vessels increasing blood pressure. Less angiotensin II activating vasopressin release inhibits blood pressure from increasing. Overall, Perindopril inhibits the conversion of angiotensin I into angiotensin II, a powerful vasoconstrictor and mediator of high blood pressure so decreasing levels of angiotensin will help reduce blood pressure from climbing in individuals.