Avtor/Urednik		Sedej, Simon; Tsujimoto, Tetsuhiro; Zorec, Robert; Rupnik, Marjan
Naslov		Voltage-activated Ca2+ channels and their role in the endocrine function of the pituitary gland in newborn and adult mice
Tip		članek
Vir		J Physiol
Vol. in št.		Letnik 555, št. 3
Leto izdaje		2004
Obseg		str. 769-82
Jezik		eng
Abstrakt		We have prepared fresh pituitary gland slices from adult and, for the first time, from newborn mice to assess modulation of secretory activity via voltage-activated Ca[sup]2+ channels (VACCs). Currents through VACCs andmembrane capacitance have been measured with the whole-cell patch-clamp technique. Melanotrophs in newborns were significantly larger than in adults. In both newborn and adult melanotrophs activation of VACCs triggeredexocytosis. All pharmacologically isolated VACC types contributed equally to the secretory activity. However, the relative proportion of VACCs differed between newborns and adults. In newborn cells L-type channels dominated and, in addition, an exclusive expression of a toxin-resistant R-type-like current was found. The expression of L-type VACCs was up-regulated by the increased oestrogen levels observed in females, and was even more emphasized in the cells of pregnant females and oestrogen-treated adult male mice. We suggest a general mechanism modulating endocrine secretion in the presence of oestrogen and particularly higher sensitivity to treatments with L-type channel blockers during high oestrogen physiological states.
Deskriptorji		AGING CALCIUM CHANNELS PITUITARY GLAND MICE ANIMALS, NEWBORN BARIUM ELECTRIC CONDUCTIVITY ESTROGENS PREGNANCY