Sources of activator calcium for potassium- and serotonin-induced constriction of isolated bovine cerebral arteries

Conference · Sat Mar 01 00:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5179235

Previous in vitro studies with the calcium channel blockers (CCB) indirectly suggest that K/sup +/ and serotonin (5HT) constrict bovine middle cerebral arteries (BMCA) by promoting the influx of extracellular calcium (Ca) through CCB-sensitive channels. In this study, the authors directly determined the sources of activator Ca for K/sup +/- and 5HT-induced constriction of BMCA, using radiolabelled /sup 4/)2%Ca and /sup 3/H-sorbitol. EGTA-resistant Ca uptake, an estimate of Ca influx into vascular smooth muscle, was determined by exposure to Ca-deficient 2 mM EGTA solutions at 1/sup 0/C. The total Ca content of BMCA was 4.4 nmole/mg (wet wt.) after equilibration at 37/sup 0/C. The total exchangeable Ca content was 1.64 nmole/mg after 1 hr of /sup 45/Ca loading; the Ca content of the extracellular water was 0.30 nmole/mg, as estimated from the /sup 3/H-sorbitol space (0.25 ul/mg). The EGTA-resistant Ca uptake at 1 hr was 134 pmole/mg. K/sup +/ and 5HT significantly increased EGTA-resistant Ca uptake during 5 min of /sup 45/Ca loading; for K/sup +/, Ca uptake increased from 71 to 202 pmole/mg, and for 5HT, from 65 to 102 pmole/mg. Verapamil (10/sup -5/ M) or nifedipine (3.3 x 10/sup -7/ M) significantly blocked the increase in EGTA-resistant Ca uptake induced by K/sup +/ or 5HT. These results provide direct evidence that K/sup +/ or 5HT may constrict BMCA by promoting the influx of extracellular Ca through CCB-sensitive channels.

• Research Organization: Temple Univ. School of Medicine, Philadelphia, PA
• OSTI ID: 5179235
• Report Number(s): CONF-8604222-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; 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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59 BASIC BIOLOGICAL SCIENCES
ARTERIES
VASOCONSTRICTION
CALCIUM
MEMBRANE TRANSPORT
POTASSIUM
BIOLOGICAL EFFECTS
SEROTONIN
CALCIUM 45
CATTLE
MUSCLES
SORBITOL
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CALCIUM ISOTOPES
CARBOHYDRATES
CARDIOVASCULAR SYSTEM
DAYS LIVING RADIOISOTOPES
DIURETICS
DOMESTIC ANIMALS
DRUGS
ELEMENTS
EVEN-ODD NUCLEI
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INDOLES
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
METALS
MONOSACCHARIDES
NEUROREGULATORS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRROLES
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
RUMINANTS
SACCHARIDES
SYMPATHOMIMETICS
TRYPTAMINES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques