Comparative study of calcium ion dynamics and contractile response in rat middle cerebral and basilar arteries.
The objective of this study was to compare intracellular calcium concentration ([Ca(2+)](i)) and contractile responses in isolated rat middle cerebral artery (MCA) with those in basilar artery (BA) employing real-time confocal laser microscopy. KCl elicited transient [Ca(2+)](i) elevation and sustained contraction in both arteries; moreover, nearly equal responses were evident in both arteries. Application of 5-hydroxytryptamine (5-HT), vasopressin (VP), and alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-me ATP) also induced elevation of [Ca(2+)](i) and contraction in both arteries. The maximum response of 5-HT and VP necessary to increase [Ca(2+)](i) and to constrict the MCA was less in comparison to the BA; however, a linear relationship emerged between the maximum response of [Ca(2+)](i) and that of contraction. Additionally, the slope of the correlation regression line of MCA was nearly identical to that of BA. On the other hand, cyclopiazonic acid (CPA)-induced Ca(2+) release from store sites following contraction of MCA was distinct from that of BA. In MCA, velocity of [Ca(2+)](i) elevation in smooth muscle cells and Ca(2+)-wave propagation along smooth muscle cells induced by 5-HT were slower than those in BA. These observations revealed that different regions of arteries along the same cerebral tissue may display distinct [Ca(2+)](i) response; moreover, this difference may be one reason for the distinct contractile response.
Department of Pharmacology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan. t-hashi@pharm.showa-u.ac.jp
Terumasa
T
Hashimoto
Hisayuki
H
Ohata
Koji
K
Nobe
Kazuo
K
Honda
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001160:Arterioles / Q000187:drug effects; D001488:Basilar Artery / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D003627:Data Interpretation, Statistical; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D020768:Middle Cerebral Artery / Q000378:metabolism / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
D000970:Antineoplastic Agents; D007211:Indoles; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014667:Vasopressins; D012701:Serotonin; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002118:Calcium; C000543:cyclopiazonic acid