Role of calcium in the constriction of isolated cerebral arteries
Calcium entry blockers (CEB) have been used in the experimental treatment or prevention of many cerebrovascular disorders including stroke, post-ischemic hypoperfusion after cardiac arrest, cerebral vasospasm after subarachnoid hemorrhage, and migraine headache. However, the mechanism of action of these drugs on the cerebral circulation is poorly understood. This study examined the effects of calcium antagonists, Ca/sup 2 +/-deficient solutions, and vasocostrictors on cerebrovascular tone and /sup 45/Ca fluxes, to determine the role of calcium in cerebral arterial constriction. A Scatchard plot of /sup 45/Ca binding to BMCA showed that Ca/sup 2 +/ was bound at either low or high affinity binding sties. The four vasoconstrictors (potassium, serotonin, PGF/sub 2 ..cap alpha../, or SQ-26,655) each increased low affinity /sup 45/Ca uptake into BMCA. The results demonstrate that: (1) Potassium and serotonin constrict BMCA mainly by promoting Ca/sup 2 +/ influx through CEB-sensitive channels; (2) PGF/sub 2 ..cap alpha../ and SQ-26,655 constrict BMCA in part by promoting Ca/sup 2 +/ influx through CEB-sensitive channels, and in part by releasing Ca/sup 2 +/ from depletable internal stores; (3) The major action of CEB on BMCA is to block vasoconstrictor-induced Ca/sup 2 +/ uptake through both potential-operated (K/sup +/-stimulated) and receptor-operated channels.
- Research Organization:
- Temple Univ., Philadelphia, PA (USA)
- OSTI ID:
- 7162099
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
AMINES
ANIMALS
AROMATICS
ARTERIES
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BLOOD VESSELS
BODY
BRAIN
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CATTLE
CENTRAL NERVOUS SYSTEM
CEREBRUM
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
DRUGS
EVEN-ODD NUCLEI
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INDOLES
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAMMALS
NERVOUS SYSTEM
NEUROREGULATORS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHYSIOLOGY
POTASSIUM COMPOUNDS
PROSTAGLANDINS
PYRROLES
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
RUMINANTS
SEROTONIN
SYMPATHOMIMETICS
TRYPTAMINES
UPTAKE
VASOCONSTRICTION
VASOCONSTRICTORS
VERTEBRATES