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The mechanism by which calcium reduces blood pressure
D Sutoo1, T Matsukura, K Akiyama
1Institute of Medical Science, University of Tsukuba, Ibaraki-Ken, Japan.
Insights
Intravenous calcium prolongs the blood pressure-lowering effects of verapamil in rats. This suggests a central calcium-calmodulin-dependent mechanism contributes to calcium
Area of Science:
- Cardiovascular Physiology
- Neuropharmacology
Background:
- Exogenous calcium's role in blood pressure regulation is not fully understood.
- Verapamil is a known calcium channel blocker that lowers blood pressure.
Purpose of the Study:
- To investigate the mechanism by which exogenous calcium affects blood pressure.
- To determine if calcium influences the effects of verapamil on blood pressure.
Main Methods:
- Conscious rats were pretreated with calcium chloride (CaCl2) intravenously before verapamil administration.
- The effect of verapamil on mean arterial pressure was measured.
- Ethylenediaminetetraacetic acid (EDTA) was injected intracerebroventricularly to assess calcium's central role.
Main Results:
- Calcium chloride pretreatment prolonged the verapamil-induced decrease in mean arterial pressure by 400%.
- Intracerebroventricular EDTA injection reduced calcium's ability to enhance verapamil's effect.
Conclusions:
- Intravenous calcium reduces blood pressure through a central mechanism.
- This central mechanism appears to be calcium-calmodulin-dependent.
Abstract:
The mechanism by which exogenous calcium reduces blood pressure was investigated. The verapamil (300 micrograms/kg i.v.)-induced decrease of the mean arterial pressure in the conscious rat was prolonged by 400% by pretreatment with CaCl2 (300 mumol/kg i.v.). This ability of calcium to enhance the effect of verapamil was decreased by i.c.v. injection of EDTA (10 nmol/kg). In light of our previous reports, these results suggest that i.v. calcium reduces blood pressure by a central calcium-calmodulin-dependent mechanism.