Avtor/Urednik     Kocmur-Bobanović, Laura
Naslov     Molekularna in fiziološka razvrstitev napetostno odvisnih kalcijevih kanalčkov v celicah srednjega režnja podganje hipofize
Tip     monografija
Kraj izdaje     Ljubljana
Založnik     Medicinska fakulteta
Leto izdaje     1996
Obseg     str. 136
Jezik     slo
Abstrakt     Calcium ions (Ca2+) mediate a wide variety of cellular responses, such as release of neurotransmitters, hormone secretion, muscle contraction, cell growth and survival and gene expression. Changes in intracellular free Ca2+ concentration are mediated by a release from intracellular stores and/or by an increased Ca2+ influx through the plasma membrane. In excitable cells such as secretory cells, the rise in intracellular calcium concentration is mainly due to calcium influx through voltage-activated calcium channels (VACC). Several types of VACC can be co-expressed in a single cell and each channel type seems to play a specific role in some functions and a co-operative role in others. Preliminary classification divided VACC into low voltage-activated (T-type) and high voltage-activated types: dihydropyridine-sensitive L-type and omega-conotoxin GVIA-sensitive N-type. The development of new toxins has pointed to the possible existence of the additional types of high voltage-activated calcium channels. Omega-agatoxin IVA blocks P-type calcium current and, with significantly lower affinity, Q-type currents which can further distinguished from P-type currents by their higher sensitivity to omega-conotoxin MVIIC. R-type current isresistant to most toxins. Molecular cloning uncovers an ever-increasing number of VACC alpha1 subunits. While both lines of investigation suggest additional complexity, the matchup between the cloned subunits and VACC is still incomplete. At the molecular level it is now accepted that alpha1S, alpha1C and alpha1D subunits carry L-type cmrrents and that als subunits cariy N-type wrrents. The alpha1A and alpha1E subunits form calcium currents which have not been definitety identified as one of the physiologically distinct types of calcium currents, but alpha1A subunits are thought to be responsible for Q-type and possibly P-type calcium currents. (Abstract truncated at 2000 characters).
Deskriptorji     PITUITARY GLAND
CALCIUM CHANNELS
CALCIUM
RATS
PATCH-CLAMP TECHNIQUES
POLYMERASE CHAIN REACTION
RNA, MESSENGER