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Calcium channels in cerebral arteries
E Alborch1, J B Salom, G Torregrosa
1Centro de Investigación, Hospital Universitario La Fe, Valencia, Spain.
Pharmacology & Therapeutics
|January 1, 1995
Summary
Voltage-operated calcium channels in cerebral arteries are crucial for tone and contraction. Calcium channel blockers can increase cerebral blood flow but may cause hypotension, limiting their use in brain protection.
Area of Science:
- Neuroscience
- Pharmacology
- Cardiovascular Physiology
Background:
- Smooth muscle cells in cerebral arteries possess voltage-operated calcium channels (L-, T-, and B-types).
- Cerebral arteries exhibit higher L-type calcium channel current intensity compared to peripheral arteries, indicating greater calcium dependence for contractions.
- Increased cytosolic calcium concentration, mediated by transmembrane influx and intracellular release, maintains basal tone and drives cerebral artery contraction.
Purpose of the Study:
- To investigate the role of voltage-operated calcium channels in cerebral arteries.
- To explore the effects of calcium channel modulators on cerebral vascular responses.
- To evaluate the potential of calcium channel blockers as cytoprotective agents in ischemic brain injury.
Main Methods:
- Electrophysiological studies to identify and characterize calcium channels.
- Assessment of contractile responses in cerebral arteries.
- In vivo studies evaluating the effects of calcium channel blockers on cerebral blood flow and systemic blood pressure.
Main Results:
- Calcium channel blockers increase pial vascular caliber and cerebral blood flow via direct action on cerebroarterial walls.
- The vasodilatory effects of calcium channel blockers are not exclusive to the brain, affecting peripheral beds and causing hypotension.
- Clinical trials for cytoprotective effects in ischemic brain damage have shown limited success, except for nimodipine in subarachnoid hemorrhage.
Conclusions:
- Voltage-operated calcium channels are key regulators of cerebral artery function.
- Calcium channel blockers have direct vasodilatory effects on cerebral arteries but systemic hypotension is a concern.
- While promising in experimental models, the clinical utility of calcium channel blockers for ischemic brain injury is restricted, highlighting the complexity of cerebrovascular regulation and drug effects.