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.
Burn scars. Severe burns that destroy large sections of skin cause the skin to heal in a puckered way. As the skin heals, muscles and tendons may be affected in this contracting movement. Keloid scars are a result of the skin's overproduction of collagen after a wound has healed.