Avtor/Urednik		Kreft, Marko; Zorec, Robert
Naslov		Cell-attached measurements of attofarad capacitance steps in rat melanotrophs
Tip		članek
Vir		Pflugers Arch
Vol. in št.		Letnik 434, št. 2
Leto izdaje		1997
Obseg		str. 212-4
Jezik		eng
Abstrakt		Capacitance changes in cell-attached patches of rat melanotrophs were measured by a high-frequency lock-in amplifier. The background noise of around 30 aF allowed the detection of discrete steps due to fission (en docytosis) and fusion (exocytosis) of vesicles with diameters as small as 60 nm. The amplitude of both types of steps was similar with a modal value of around 300 aF. The frequency of these steps was not changed, if secretagougues such as ionomycin and/or dibutyril cAMP, were applied to the bathing solution. Moreover, this treatment did not result in an increased appearance of expected 2000 to 3000 aF steps due to exocytosis of secretory granules. We conclude that the likely explanation for recorded capacitance steps is that they represent the constitutive vesicle traffic. From the typical freduency and amplitude of these events (around 1 min-1, 300 aF) in a membrane patch (26 fF) it is estimated that the whole membrane of a rat melanotroph may be ingested under our conditions in 1 to 2 h.
Deskriptorji		PITUITARY GLAND EXOCYTOSIS ENDOCYTOSIS PATCH-CLAMP TECHNIQUES IONOMYCIN DIBUTYRYL CYCLIC GMP RATS, WISTAR