Abstract
Gallbladder (GB) motility diminishes with aging. This study was performed to characterize mechanisms that are involved in changes in GB contractility that occur during aging. Cytoplasmic Ca2+ concentrations ([Ca2+](i)) and the contractile force of guinea pig GB muscle strips were simultaneously measured using fura-2 and force-displacement transducers. The binding ability of the Ca2+ channel antagonist and GB muscle compliance were also examined. The COOH-terminal octapeptide of cholecystokinin (CCK-8) evoked a dose- dependent increase in force and [Ca2+](i). Changes of [Ca2+](i) and contractile force of muscle strips in response to CCK-8 were significantly greater in young (2 mo old) compared with mature and aged (12 and 24 mo old) guinea pigs (changes in [Ca2+](i), ED50: 46.1 nM at 2 mo, 6.1 μM at 12 mo, and 2.8 mM at 24 mo; changes of contractile force, ED50: 24.8 μM at 2 mo, 2.1 mM at 12 mo, and 357 mM at 24 mo). However, the magnitude of the contraction at each percent change in [Ca2+](i) was actually similar in young and aged guinea pigs. In a Ca2+-free buffer, the responses of [Ca2+](i) and force to CCK-8 in both young and aged GB muscles decreased, but those were still dose and age dependent. Binding ability of the Ca2+ channel antagonist did not differ in the young and aged groups, but the compliance of the GB muscle strip decreased with aging. These results suggest that both a reduced mobilization of intracellular Ca2+ and a decreased muscle compliance are responsible, at least in part, for age-related reduced contraction of guinea pig GB in response to CCK.
Original language | English (US) |
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Pages (from-to) | G624-G629 |
Journal | American Journal of Physiology - Gastrointestinal and Liver Physiology |
Volume | 264 |
Issue number | 4 27-4 |
DOIs | |
State | Published - 1993 |
Externally published | Yes |
Keywords
- aging
- antagonist
- calcium channel
- compliance
- fura-2
- motility
- tension
ASJC Scopus subject areas
- Physiology
- Hepatology
- Gastroenterology
- Physiology (medical)