Alveolar Myofibroblasts Contractile Interstitial Cells

There are two distinct fibroblast subtypes in the neonatal rat lung. The lipid interstitial cell (LIC) accumulates lipid, contains lipoprotein lipase, and myofilaments. The non-lipid interstitial (NLIC) cell does neither contain lipoprotein lipase nor abundant myofibrils. Villanueva et al. (1988) treated both subtypes with TGF-P, an effector molecule that stimulates embryonic fibroblasts to produce collagen and fibronectin. TGF-p caused a significant increase in collagen and total protein production in LIC cultures, as measured by the amount of nondialyzable [ H]hydroxyproline and [ HJproline incorporated into proteins over 24 h. Parallel changes in the amounts of total nanomoles of nondialyzable hydroxyproline indicated that these increases were not the result of alteration in proline pool size. TGF-P did not stimulate an increase in collagen formation by NLIC cultures. 

Photoprotection of parenteral multivitamin solutions or total parenteral nutrition prevented light induction of procollagen mRNA in the lungs of 3-day-old guinea pig pups (Lavoie et al. 2002). The effect of parenteral multivitamin solutions -1- light was associated with a peroxide load coupled with a low glutathione level. This was also observed with a 500 /iM 

H2O2 group. The addition of GSSG prevented the increase of procollagen mRNA caused by HjOj. 

The hydrox)dation system consists of bivalent iron complex bound by ethylenediamine tetraacetic acid (formula [187]), ascorbic acid (formula [53]), and hydrogen peroxide (Brodie et al. 1954, Udenfriend et al. 1954). In vitro, the major amount of hydroxyproline was formed during the first 30 s (Hurych 1967). If the proline in the incubation mixture was replaced by hydroxyproline a decomposition of about 30 % of the hydroxyproline occurred. Accordingly, the newly formed hydroxyproline was the result of synthetic and degradation processes, which are caused, as is generally assumed (Haber and Weiss 1934, Kolthoff and Medalia 1949), by free radicals. 

Chvapil et al. (1974) studied the effect of both Fe and Fe chelating agents in tissues with a relatively high rate of collagen synthesis such as foetal skin and skin of newborn rats, 17P-oestradiol-stimulated uterus of immature rats, and carrageenan granuloma tissue. Neither systemic nor local injections of 

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