ISSN:
1432-1912
Keywords:
Key words: Macrophage – Voltage-clamp – Potassium current – Zymosan – Platelet activating factor – Calcium ionophore A 23187
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract. The effects of zymosan and human serum opsonized zymosan on membrane currents of adherent mouse peritoneal macrophages which had been cultured for 5 to 20 days were investigated with the whole-cell voltage-clamp technique. Both stimuli activated an outward current. The outward current activation was transient and lasted about 5 min. In solutions with 10 or 50 mmol/l extracellular potassium concentration the activation of an outwardly directed current occurred at test potentials positive to the respective potassium equilibrium potential. This particle-induced current resembled a calcium-activated potassium current which could be activated with the calcium ionophore A 23187 and with platelet activating factor. The order of maximal responses (test potential +55 mV, amplitude given as percentage of the respective control) was: 0.1 μmol/l platelet activating factor (222±36%, n=8, P〈0.01) 〈1 μmol/l A 23187 (190±24%, n=11, P〈0.01) 〈900 μg/ml opsonized zymosan (134±7%, n=22, P〈0.01) 〈900 μg/ml zymosan (116±5%, n=21, P〈0.01). The lower efficiency of zymosan as compared to opsonized zymosan is explained in part by a lower percentage of responding cells which was 48% for zymosan and 73% for opsonized zymosan. Macrophages which were pretreated with particles showed a greater reactivity to calcium as compared to untreated cells. Elevation of extracellular calcium from 0.9 to 4.5 mmol/l activated the outward current to 145±12% (n=11, P〈 0.01) after preincubation with opsonized zymosan and to 144±21% (n=12, P〈0.01) under the influence of zymosan while in untreated cells current increase by elevation of extracellular calcium was not significant (120±10%, n=9, n.s.).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01258465
