Developmental changes in ryanodine- and IP(3)-sensitive Ca(2+) pools in ovine basilar artery.
To explore the hypothesis that cerebrovascular maturation alters ryanodine- and inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) pool sizes, we measured total intracellular Ca(2+) with (45)Ca and the fractions of intracellular Ca(2+) released by IP(3) and/or caffeine in furaptra-loaded permeabilized basilar arteries from nonpregnant adult and term fetal (139-141 days) sheep. Ca(2+) mass (nmol/mg dry weight) was similar in adult (1.60 +/- 0.18) and fetal (1.71 +/- 0.16) arteries in the pool sensitive to IP(3) alone but was significantly lower for adult (0.11 +/- 0.01) than for fetal (1.22 +/- 0.11) arteries in the pool sensitive to ryanodine alone. The pool sensitive to both ryanodine and IP(3) was also smaller in adult (0.14 +/- 0.01) than in fetal (0.85 +/- 0.08) arteries. Because the Ca(2+) fraction in the ryanodine-IP(3) pool was small in both adult (5 +/- 1%) and fetal (7 +/- 4%) arteries, the IP(3) and ryanodine pools appear to be separate in these arteries. However, the pool sensitive to neither IP(3) nor ryanodine was 10-fold smaller in adult (0.87 +/- 0.10) than in fetal (8.78 +/- 0.81) arteries, where it accounted for 72% of total intracellular membrane-bound Ca(2+). Thus, during basilar artery maturation, intracellular Ca(2+) mass plummets in noncontractile pools, decreases modestly in ryanodine-sensitive pools, and remains constant in IP(3)-sensitive pools. In addition, age-related increases in IP(3) efficacy must involve factors other than IP(3) pool size alone.
Nauli
S M
SM
Department of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California 92350, USA.
Williams
J M
JM
Akopov
S E
SE
Zhang
L
L
Pearce
W J
WJ
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects* / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005333:Fetus; D006160:Guanosine Triphosphate / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D009119:Muscle Contraction / Q000502:physiology; D012433:Ryanodine / Q000494:pharmacology*; D012756:Sheep; D013050:Spectrometry, Fluorescence; D014638:Vanadates / Q000494:pharmacology
D000697:Central Nervous System Stimulants; D007476:Ionophores; D012433:Ryanodine; D000001:Calcimycin; D002110:Caffeine; D014638:Vanadates; D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate; D002118:Calcium