Ion Channel Assessment - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 501

ion channel expression and function after SAH. At some point,
principles of Ca 2+ channel assessment exemplary should be
pointed for ion channel in general.

2. Materials
and Instruments

Material and instruments required for ion channel assessment
depends on the used procedures. However, usually standard labo-
ratory equipment, such as PCR-cycler, centrifuges, etc., is needed.
This standard equipment can be supplemented by special equip-
ment. Furthermore, for various methods commercial kits are avail-
able which usually provide a comparatively easy way to perform a
particular method—especially for beginners.

3. Procedures

Assessment of the role of ion channels during SAH-mediated
vasospasm includes the wide-spread spectrum of molecular-biolog-
ical, electrophysiological, immunochemical, and functional meth-
ods evaluating ion channel expression and function as well as the
mediated currents. Standard molecular biological assessment of
expression of ion channels and their tissue distribution in healthy
and vasospastic cerebral vessels includes the evaluation of ion
channel transcripts [e.g., by reverse transcription-polymerase chain
reaction (RT-PCR)], confi rmation of proteins (usually by SDS-
PAGE and subsequent Western-blot analysis) or analysis of channel
distribution by immunohistological staining. The mediated cur-
rents can be measured as whole-cell recordings as well as single-cell
recordings by patch clamp analysis.

3.1. When Should Ion
Channel Assessment
Be Performed?

For success of the analysis, defi nition of several parameters is impor-
tant: probably, changes in calcium channel function and expression
occur at different time points refl ecting a dynamic process of induc-
tion of cerebral vasospasm after aneurysmal SAH. Therefore, defi ni-
tion of the time range, respectively, the time points of ion channel
analysis seems to be critical. The time course varies among different
animal models of SAH-induced cerebral vasospasm probably due to
species-related differences in the clot clearance and structural differ-
ences in the vascular and perivascular elements ( 14-19 ). In various
animal models, delayed cerebral vasospasm could be distinguished
from direct acute effects of oxy-hemoglobin on voltage-gated ion
channels. Acute effects were suggested to depend on suppression
of voltage-gated K + channel currents, while delayed vasospasm
involves also expression of voltage-gated Ca 2+ channels ( 20 ). At
best, ion channel assessment should refl ect changes in channel