Biomedical subjects

M F Cossu

Publications and source records attributed to M F Cossu.

3 recordsLinked to original sources

PubMed1986

Involvement of the Ca2+-dependent K+ channel activity in the hyperpolarizing response induced by epidermal growth factor in mammary epithelial cells.

Epidermal growth factor (EGF) induces a hyperpolarizing response of 5-20 mV amplitude in mouse mammary epithelial cells in culture. The amplitude of the hyperpolarizing response was reduced by more than 60% within several minutes after addition of blockers of voltage and/or Ca2+-dependent K+ channels such as tetraethylammonium (7 mM) or quinine (0.29 mM). Both nifedipine (0.15 mM), a blocker of the Ca2+ channel, and ruthenium red (2 mM), an inhibitor of the Ca2+-binding site, also reduced the amplitude of the hyperpolarizing response by more than 60%. The Ca2+ ionophore, A23187 (3.8 microM), induced a large hyperpolarization, which was 25-40 mV and lasted about 3 min. These data suggest that activity of the Ca2+-dependent K+ channel was involved in the EGF-induced hyperpolarizing response of the mammary epithelial cells.

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PubMed1986

Induction of distinct types of spontaneous electrical activities in mammary epithelial cells by epidermal growth factor and insulin.

Electrophysiological measurements of the membrane potentials of mouse mammary epithelial cells in primary culture revealed the presence of spontaneous-oscillating-hyperpolarizing potentials in cells incubated with epidermal growth factor. The hyperpolarizing potentials were 5-20 mV in amplitude and about 10 sec in duration. The peak height of the response was reduced by hyperpolarization, and the input membrane resistance decreased during the response. The response was probably due to activation of K+ channels. The latency period for the epidermal growth factor induction of the hyperpolarizing potential was approximately 3 hr. In contrast, insulin induced spontaneous-depolarizing potentials that were about 5 mV in amplitude and 1 sec in duration. The depolarizing potentials were attributed to activity of ion channels, since the peak height was dependent on the membrane potential and the depolarizing potential was accompanied by a decrease of input membrane resistance. The time lag for the induction of the depolarizing potential was 6-12 hr. Other hormones involved in mammary cell differentiation, such as cortisol and prolactin, neither induced the depolarizing potentials nor changed the induction of depolarizing potential by insulin. In addition, other growth factors, such as nerve growth factor and fibroblast growth factor, elicited no electrical activity.

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PubMedDate not supplied

[The IgE system].

The IgE synthesis is regulated by a system of immunocompetent cells (B and T lymphocytes) and cytokines (IL-4, IFN gamma, IL-2, IL-5, IL-6) produced by T cells as a response to antigenic stimuli. IL-4 alone, or associated with other cytokines, determines the CD23+ receptor (FCERII) expression on monocytes-macrophages, eosinophiles, platelets, epidermidis Langerhans cells and B lymphocytes surfaces, inducing its cleavage in a Soluble Factor (IgE-BF), that increases the IgE synthesis. IFN-gamma, on the other hand, plays an inhibitory role on T-dependent phenomena, IL-4-mediated. In patients affected by atopic diseases, associated with oculorhinites, dermatitis and hyper-IgE syndrome, are found high serum levels of IgE, eosinophiles, and a large number of CD23+ cells: this indicates the hyper-reactivity of the IgE system and the IL-4 overproduction.

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