Characteristics of Ca2+ stores in rabbit cerebral artery myocytes.
- Author:
Sung Joon KIM
1
;
Jin Kyung KIM
;
Insuk SO
;
Suk Hyo SUH
;
Sang Jin LEE
;
Ki Whan KIM
Author Information
1. Department of Physiology & Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea.
- Publication Type:Original Article
- Keywords:
Smooth muscle;
Ca2+ concentration;
Ca2+ pool;
Histamine;
Caffeine
- MeSH:
Baths;
Caffeine;
Cerebral Arteries*;
Cytoplasm;
Fura-2;
Hand;
Histamine;
Muscle Cells*;
Muscle, Smooth;
Ryanodine;
Ryanodine Receptor Calcium Release Channel;
Sarcoplasmic Reticulum
- From:The Korean Journal of Physiology and Pharmacology
1998;2(3):313-322
- CountryRepublic of Korea
- Language:English
-
Abstract:
In a myocyte freshly isolated from rabbit cerebral artery, the characteristics of Ca2+ release by histamine or caffeine were studied by microspectrofluorimetry using a Ca2+-binding fluorescent dye, fura-2. Histamine (5 micrometer) or caffeine (10 mM) induced a phasic rise of cytoplasmic free Ca2+ concentration ((Ca2+)c) which could occur repetitively with extracellular Ca2+ but only once or twice in Ca2+-free bathing solution. Also, the treatment with inhibitor of sarcoplasmic reticulum Ca2+-ATPase suppressed the rise of (Ca2+)c by histamine or caffeine. In Ca2+-free bathing solution, short application of caffeine in advance markedly attenuated the effect of histamine, and vice versa. In normal Ca2+-containing solution with ryanodine (2 micrometer), the caffeine-induced rise of (Ca2+)c occurred only once and in this condition, the response to histamine was also suppressed. On the other hand, in the presence of ryanodine, histamine could induce repetitive rise of (Ca2+)c while the amplitude of peak rise became stepwisely decreased and eventually disappeared. These results suggest that two different Ca2+-release mechanisms (caffeine-sensitive and histamine-sensitive) are present in rabbit cerebral artery myocyte and the corresponding pools overlap each other functionally. Increase of (Ca2+)c by histamine seems to partially activate ryanodine receptors present in caffeine-sensitive pool.
