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.
During osteoarthritis, the most common form of arthritis, this regulation is disrupted by the expression of pro-inflammatory molecules that provides the stimulus for the synthesis of matrix-degrading enzymes. These enzymes degrade aggrecan and collagen, resulting in the loss of cartilage and function.