Effects of calmodulin and calmodulin inhibitors on Ca uptake by sarcoplasmic reticulum of saponin skinned caudal artery
Calmodulin (CaM) stimulates plasma membrane transport in many cell types, however, its role in Ca regulation by the sarcoplasmic reticulum (SR) in smooth muscle has not been established. /sup 45/Ca uptake was studied in saponin skinned strips of rat caudal artery as a function of CaM and the CaM inhibitors, W-7, calmidazolium (CaMZ), and trifluoperazine (TFP). Although caudal artery strips lose approximately 30% of total tissue CaM during skinning, 0.3 - 2 ..mu..M CaM did not increase /sup 45/Ca uptake over a wide range of free Ca concentrations (10/sup -8/ - 10/sup -6/M). Neither W-7 nor CaMZ at concentration of 10/sup -4/ - 2 x 10/sup -4/M inhibited the MgATP-dependent Ca uptake. Ca uptake was not affected by 50 ..mu..M TFP but a significant inhibition was produced by 500 ..mu..M. Studies of the effects of TFP on /sup 45/Ca efflux indicated that TFP concentrations which inhibited Ca uptake also significantly increased the rate of Ca release. The results suggest that total Ca uptake in caudal artery depends mainly upon MgATP and is not modulated by exogenous CaM or affected by these CaM inhibitors. They cannot preclude that CaM may affect initial velocities or that the CaM inhibitors failed to reach active sites.
- Research Organization:
- WMO-New Jersey Medical School, Newark
- OSTI ID:
- 7189549
- Report Number(s):
- CONF-8604222-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM
UPTAKE
PROTEINS
BIOLOGICAL EFFECTS
ARTERIES
CALCIUM 45
MEMBRANE TRANSPORT
MUSCLES
SARCOPLASMIC RETICULUM
TRACER TECHNIQUES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CALCIUM ISOTOPES
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
METALS
NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques