Table 3 Culture growth of activated human hepatic stellate cells was determined using [³H] thymidine incorporation.

Compound	Pharmacological activity	Proliferation index
Serum free media (SF)	–	100 (00)
SF+DPDPE	δ1 receptor agonist	89 (9)
SF+deltorphin II	δ2 receptor agonist	127 (49)
SF+PDGF‐BB	Growth factor	398 (88)*
Fetal calf serum (SP)	Growth factor	1524 (1193)*
SP+DPDPE	Growth factor/δ1 receptor agonist	1065 (863)*
SP+deltorphin II	Growth factor/δ2 receptor agonist	1316 (913)*
SP+PDGF‐BB	Growth factor/growth factor	1828 (1432)*

Following 24 hours of serum starvation, cells were cultured for an additional 16 hours in serum supplemented (16%) or serum free media in the presence of DPDPE or deltorphin II (selective δ₁ and δ₂ receptor agonists, respectively) or recombinant human platelet derived growth factor (PDGF‐BB) prior to addition of [methyl‐³H] thymidine. Cells were incubated for a further 24 hours before washing with Hanks balanced salt solution and fixing.

Data are presented as mean (SEM) of three double experiments (n = 3).

*p<0.05 compared with serum free group.