Table 3.

Effects of mechanical strain on major second messengers.

Second messenger	Experimental condition (expansion or stress)	Effects on second messenger	Major observation	References
Cyclic adenosine monophosphate (cAMP)	Cyclical elongation and relaxation of smooth muscle cells grown on elastic membrane	↑	Collagen production inhibited by raised cAMP.	Kollros et al., 1987
	Round tissue expanders were placed dorsally	↓	Protein production increased in expanded tissue	Johnson et al., 1988
	Constant and cyclic strain (150 mmHg for 5 days) of human keratinocytes	↓	Protein production significantly increased	Takei et al., 1997
Prostaglandin E2 (PGE2)	Cyclical elongation and relaxation of smooth muscle cells grown on elastic membrane	↑	Collagen production inhibited by increased PGE2.	Kollros et al., 1987
	Constant and cyclic strain (150 mmHg for 5 days) of human keratinocytes	↓	Protein production significantly increased	Takei et al., 1997
Phosphodiesterase IV (PDE IV)	Constant and cyclic strain (150 mmHg for 5 days) of human keratinocytes	↑	Controll cAMP levels in human keratinocytes	Takei et al., 1997

↑, increased in response to mechanical strain; ↓, decreased in response to mechanical strain.