Adenosine 3′:5′-cyclic monophosphate in young and senescent human fibroblasts during growth and stationary phase in vitro. Effects of prostaglandin E1 and of adrenaline

Abstract

Cyclic AMP levels per mg of cell protein were higher in late-passage (senescent) fibroblasts than in early-passage (young) fibroblasts both during growth and stationary phase, but, because the protein concentration per unit volume in senescent cells was lower than in young cells, the molar concentrations of intracellular cyclic AMP were very similar in the two cell types. In both young and senescent fibroblasts cyclic AMP levels declined during growth and no increase in intracellular cyclic AMP occurred in association with density-dependent inhibition of growth. These results indicate that changes in cyclic AMP concentration do not play a role in controlling the growth or in the senescent decline of human fibroblasts. Prostaglandin E(1) (1mum) caused maximal increases in fibroblast cyclic AMP concentration of 60-500-fold after 10-30min, and adrenaline (epinephrine) (10mum) caused maximum increases of 5-25-fold after 2-10min, depending on both the number of passages and the period after subculture. The cyclic AMP level in confluent young cells increased more with prostaglandin E(1) and far less with adrenaline than the cyclic AMP level in confluent senescent cells. During growth to confluence the cyclic AMP response to adrenaline declined in young cells and increased in senescent cells. As these responses to prostaglandin E(1) and to adrenaline changed independently of each other and of the basal cyclic AMP concentration, it is suggested that the expression of hormone receptors is altered both during growth to confluence and during senescence of human fibroblasts.

Enhanced Adenosine 3': 5' - Monophosphate Response to Betaadrenergic Stimulation in Cystic Fibrosis Fibroblasts After Removal of Conditioned Medium

“…Thus, if donor fibroblasts preserve their typical pattern of 8-receptors throughout the period of cultivation, the age of donor fibroblasts could possibly influence adrenergic responsiveness of cultured cells. Cultured fibroblasts appear to be more sensitive to catecholamines with increasing number of passages (14). Therefore in this study all fibroblast strains were from donors of about the same age and were used within the same passage number.…”

“…It is difficult, however, to compare the results of the different studies since many factors can modify the cyclic nucleotide synthesis in cultured cells. Culture conditions such as passage number (14), cell density ( 1 6 ) , time after subculture (20), serum concentration (19) and stage of the cell cycle (25) have been shown to influence signiEicantly the response of the cAMP system. We therefore reinvestigated CAMP response to 0-adrenergic stimuli in cultured fibroblasts from CFpatients and from normal controls using strictly defined culture conditions and examined the contribution of the conditioned culture medium to this system.…”

Hormone-stimulated Cyclic AMP Production by Skin Fibroblasts Cultured from Healthy Persons and Patients with Cystic Fibrosis

“…Cell number increased for about 5 days aAer subculture in all conditions tested and then remained stable; doubling time (24 to 36 hr) was the same in all conditions tested. Also, hormone-responsiveness of cAMP content has been shown to vary with time after subculture (16,20). In these experiments (Fig.…”

“…Cultured fibroblasts are endowed with the abnormal genetic material yet are remote from the influences of drugs and illness to which the patient is subject, and the biochemical milieu of the fibroblast can be manipulated to a far greater extent than the intact human organism. Fibroblasts possess an adrenergic-responsive adenylate cyclase (EC 4.6.1.1) system (16,20), and the direction of the adenylate cyclase response to isoproterenol in skin fibroblasts from normal and cystic fibrosis (CF) donors has been controversial in the literature. Buchwald (4) first reported that C F fibroblasts produced more cyclic adenosine 3'5'-monophosphate (CAMP) in response to isoproterenol than normal fibroblasts.…”

“…Cellular cAMP content varies with the cell cycle: human fibroblasts in the logarithmic phase have higher cAMP content than confluent cells (16), although in other cultured cells the pattern is reversed (6). Thus, if fibroblasts from normal persons and C F patients grew at different rates, differences in cellular cAMP content might result.…”