Anabolic steroids are synthetic substances related to male sex hormones (androgens). Although it is illegal in the United States to possess or distribute anabolic steroids for nonmedical use, a "black market" for them exists, and many amateur and professional athletes take them to enhance performance. In many cases, the athletes take doses that are extremely high—perhaps 100 times the doses that might be prescribed for medical use. As a result, they put themselves in real danger of short-term and long-term health problems. Blood testing, as has been used in the Olympic Games, can detect, identify, and quantify the presence of anabolic steroids in the blood of athletes, which can lead to the disqualification of an athlete.
Calcium ions are one type of second messengers and are responsible for many important physiological functions including muscle contraction, fertilization and neurotransmitter release. The ions are normally bound or stored in intracellular components (such as the endoplasmic reticulum) and can be released during signal transduction. The enzyme phospholipase C produces diacylglycerol and inositol trisphosphate , which increases calcium ion permeability into the membrane. Active G-protein open up calcium channels to let calcium ions enter the plasma membrane. The other product of phospholipase C, diacylglycerol, activates protein kinase C , which assists in the activation of cAMP (another second messenger).