Assessment of Intracellular Calcium in Cerebral Artery Myocytes

Vascular tone and consequently, cerebral blood flow, are regulated by the concentration of global cytosolic Ca²⁺ (global [Ca²⁺ ]_i ) in vascular smooth muscle. Global [Ca²⁺ ]_i is, in part, regulated by discrete Ca²⁺ release events from the sarcoplasmic reticulum (Ca²⁺ sparks) which activate plasma membrane large conductance Ca²⁺ -activated K⁺ channels to cause membrane potential hyperpolarization, decreased global [Ca²⁺ ]_i , and vasodilation. We have previously observed decreased Ca²⁺ spark frequency and elevated global [Ca²⁺ ]_i in cerebral artery myocytes using a rabbit model of subarachnoid hemorrhage. Here, we describe and discuss laboratory methods and procedures using the fluorescent Ca²⁺ indicator dyes fura-2 and fluo-4 to assess global and local Ca²⁺ signaling in cerebral arteries and isolated vascular myocytes.