Inhibition of Adenylate Cyclase: The muscarinic receptor, through interaction with an inhibitory GTP-binding protein, acts to inhibit adenylyl cyclase. Reduced cAMP production leads to reduced activation of cAMP-dependent protein kinase, reduced heart rate, and contraction strength.
Scleroderma, a rare autoimmune disease characterized by abnormal connective tissue growth, can wreak havoc on everything from the skin and heart to lungs, teeth, speech, and movement. The overproduction of collagen causes the skin and organs to harden, leading them to atrophy and possibly fail.
Collagen occurs throughout the body, but especially in the skin, bones, and connective tissues. Some types of collagen fibrils, gram-for-gram, are stronger than steel. Collagen production declines with age and exposure to factors such as smoking and UV light. Collagen can be used in collagen dressings, to attract new skin cells to wound sites. Cosmetic lotions that claim to increase collagen levels are unlikely to do so, as collagen molecules are too large to be absorbed through the skin.