Biology Reference
In-Depth Information
Chapter 39
Electrophysiological Assessment of Cerebral Vasospasm
Jinglu Ai and R. Loch Macdonald
Abstract
Cerebral vasospasm is chiefl y due to sustained abnormal contraction of smooth muscle cells. Vasospasm
develops several days after subarachnoid hemorrhage (SAH) and resolves after 10-14 days. Electrophysiological
techniques have been used by several laboratories to elucidate some of the mechanisms involved in experi-
mental vasospasm, including roles of calcium, potassium and transient receptor potential (TRP) channels.
The purpose of this chapter is to briefl y introduce the instrumentation, materials and procedures for using
electrophysiology techniques to study the functional role of ion channels and receptors in smooth muscle
cells or potentially other neuronal cells in the brain that may mediate vasospasm and/or brain dysfunction
after SAH.
Key words:
Cerebral vasospasm, Ion channel, Subarachnoid hemorrhage, Transient receptor potential
1. Introduction
Cerebral vasospasm is transient narrowing (
1
) of intradural suba-
rachnoid arteries that occurs several days after subarachnoid
hemorrhage (SAH) and can cause ischemia, stroke, and death.
Vasospasm is chiefl y due to sustained abnormal contraction of
smooth muscle cells in the arteries. How and why this occurs is not
fully understood. However, recent studies using electrophysiologi-
cal techniques have elucidated some of the mechanisms of vasos-
pasm that may involve calcium (Ca
2+
), potassium (K
+
) and transient
receptor potential (TRP) channels in isolated smooth muscle cells
from arteries of various animal models of SAH (
1-10
). Electro-
physiology, in a narrow sense, here refers to patch-clamp techniques,
which were invented by Neher and Sakmann in the late 1970s and
early 1980s (
11
). This technique is a very powerful tool for studying
the normal or abnormal physiological behaviours of many kinds
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