Free Secrets of Your Cells: Discovering Your Body's Inner Intelligence by Sondra Barrett

more than membrane receptors, something you will learn more about in the next chapter. The ultimate aim of a molecule binding to its receptor (if molecules have goals) is to turn the cell on for a specific activity. Examples of cellular activities include making more energy, slowing down, and contracting. You can envision the interaction as a molecular embrace: the receptor has to “hug” the signaling molecule. If the squeeze is too tight, the “on” switch may stay on too long; if it’s too loose, the cell might not even know it’s supposed to do anything. It’s the “just right” connection that encourages the cell to change what it’s doing and take a different action.
    One of our first insights into the importance of cell receptors began around sixty years ago when researchers examined how adrenaline works. Adrenaline, also known as epinephrine, is a molecular signal of distress that tells our bodies to get ready for action. It ensures that there is enough sugar in the blood to keep things going by facilitating liver cells to free glucose from its storage form, called glycogen, and release it into the blood. Stress (the fight-or-flight response), which can be triggered by an acute physical or mental challenge, creates a chemical drumroll that moves energy to our muscles, increases blood pressure to get oxygen to the cells, and accelerates everything needed for immediate survival. If the cell receives a message of danger, it enables us to fight or run away. Almost every cell type in the body has receptors for adrenaline, though each responds in its own specific way. Heart cells beat faster in the presence of adrenaline, while cells in the pancreas stop secreting insulin. Every part of us has a job to do to deliver us from danger. 2 To give you a sense of different receptor shapes, compare the form of adrenaline (see plate 8 in the color insert) to the form of caffeine (see plate 9 in the color insert). You can easily see that cells need different kinds of receptors to respond to the diversity of chemicals.
If you were to assign a different color to each of the receptors that scientists have identified, the average cell surface would appear as a multicolored mosaic of at least 70 different hues—50,000 of one type of receptor, 10,000 of another, 199,000 of a third and so forth.
— CANDACE PERT Molecules of Emotion
    Masquerading Molecules
    Our bodies produce thousands of different molecular messages, and drug developers have taken advantage of this fact by synthesizing “impostor” messages that mimic the chemistry and shape of our natural molecules. In fact, many drugs used in medicine today achieve their results by preventing natural signals from engaging their receptors. For example, drugs known as beta blockers—frequently given to lower blood pressure—fit some of the adrenaline receptors and prevent our own adrenaline from sending its information. In so doing, they prevent or lessen the adrenaline’s signal to “get ready for action” and keep the heart from racing. 3
    These imposter molecules can have wide-ranging effects. When I was getting ready to give my first talk to the American Heart Association, my boss, a cardiologist, asked whether I wanted to take propranolol, a beta blocker, to ease my nervous, racing heart; people who are terrified of speaking in public or taking exams sometimes resort to popping one of these before the stressful event. Though I chose to use natural methods—I meditated beforehand instead of medicating—it is fascinating that altering communication on a cellular level can both ease the physical condition of hypertension and powerfully impact our emotional experience.
    Call for Rescue
    The continual ebb and flow of molecular messages is essential to life and survival. When in danger, the cell calls for help, alerts its allies,and demands energy. Equipped with a chemical repertoire of molecular messages, it engages neighboring and distant cells in common action. When