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.
In someone suffering with scleroderma, collagen (a protein manufactured by the connective tissues of the body) is produced in excess. This over-production of collagen can be likened to the process of scarring, which is the way the body heals a wound. For persons with scleroderma, the scarring gets out of hand.
In scleroderma, the immune system is thought to stimulate cells called fibroblasts to produce too much collagen. In scleroderma, collagen forms thick connective tissue that builds up around the cells of the skin and internal organs. In milder forms, the effects of this buildup are limited to the skin and blood vessels.