Abstract
The electrophysiological effects of diltiazem were studied in right ventricular muscle fibers from normal cats and cats with experimentally induced right ventricular systolic hypertension (RVSH). Two types of action potential (AP) abnormalities were observed in preparations from cats with RVSH: Type I cells, found in most areas of the right ventricular free wall, demonstrated reduced maximum diastolic potential (MDP) (-64.4 mV) and V̇[max] (89.6 V/s) while Type II cells showed a 'slow response' AP configuration (MDP, -48.8 mV; AP amplitude, 48.9 mV; AP duration at 50% repolarization, 47.5 ms; AP duration at 90% repolarization, 90.2 ms; V̇[max], 13,1 V/s) and were often monitored near the tricuspid valve. Diltiazem (2.2 x 10 -7 and 2.2 x 10 -6 M) had no effect on MDP of normal, Type I, or Type II cells. Diltiazem at 2.2 x 10 -6 M significantly reduced AP amplitude and V̇[max] of both Type I and normal cells. In contrast, even at 2.2 x 10 -7 M, diltiazem significantly reduced AP amplitude and V[max] of the Type II cells. Diltiazem, 2.2 x 10 -6 M, would often abolish AP of Type II cells, while Type I cells were more sensitive to tetrodotoxin. AP duration of normal cells was unaffected by diltiazem while that of Type I and II cells was significantly shortened.
| Original language | English |
|---|---|
| Pages (from-to) | 986-993 |
| Number of pages | 8 |
| Journal | Journal of Cardiovascular Pharmacology |
| Volume | 4 |
| Issue number | 6 |
| State | Published - Dec 1 1982 |
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ASJC Scopus subject areas
- Pharmacology
- Cardiology and Cardiovascular Medicine
Cite this
Effects of diltiazem on the electrophysiological properties of cat ventricular muscle fibers during experimentally induced right ventricular systolic hypertension. / Wong, S. S.; Myerburg, Robert J; Ezrin, A. M.; Gaide, M. S.; Bassett, A. L.
In: Journal of Cardiovascular Pharmacology, Vol. 4, No. 6, 01.12.1982, p. 986-993.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effects of diltiazem on the electrophysiological properties of cat ventricular muscle fibers during experimentally induced right ventricular systolic hypertension
AU - Wong, S. S.
AU - Myerburg, Robert J
AU - Ezrin, A. M.
AU - Gaide, M. S.
AU - Bassett, A. L.
PY - 1982/12/1
Y1 - 1982/12/1
N2 - The electrophysiological effects of diltiazem were studied in right ventricular muscle fibers from normal cats and cats with experimentally induced right ventricular systolic hypertension (RVSH). Two types of action potential (AP) abnormalities were observed in preparations from cats with RVSH: Type I cells, found in most areas of the right ventricular free wall, demonstrated reduced maximum diastolic potential (MDP) (-64.4 mV) and V̇[max] (89.6 V/s) while Type II cells showed a 'slow response' AP configuration (MDP, -48.8 mV; AP amplitude, 48.9 mV; AP duration at 50% repolarization, 47.5 ms; AP duration at 90% repolarization, 90.2 ms; V̇[max], 13,1 V/s) and were often monitored near the tricuspid valve. Diltiazem (2.2 x 10 -7 and 2.2 x 10 -6 M) had no effect on MDP of normal, Type I, or Type II cells. Diltiazem at 2.2 x 10 -6 M significantly reduced AP amplitude and V̇[max] of both Type I and normal cells. In contrast, even at 2.2 x 10 -7 M, diltiazem significantly reduced AP amplitude and V[max] of the Type II cells. Diltiazem, 2.2 x 10 -6 M, would often abolish AP of Type II cells, while Type I cells were more sensitive to tetrodotoxin. AP duration of normal cells was unaffected by diltiazem while that of Type I and II cells was significantly shortened.
AB - The electrophysiological effects of diltiazem were studied in right ventricular muscle fibers from normal cats and cats with experimentally induced right ventricular systolic hypertension (RVSH). Two types of action potential (AP) abnormalities were observed in preparations from cats with RVSH: Type I cells, found in most areas of the right ventricular free wall, demonstrated reduced maximum diastolic potential (MDP) (-64.4 mV) and V̇[max] (89.6 V/s) while Type II cells showed a 'slow response' AP configuration (MDP, -48.8 mV; AP amplitude, 48.9 mV; AP duration at 50% repolarization, 47.5 ms; AP duration at 90% repolarization, 90.2 ms; V̇[max], 13,1 V/s) and were often monitored near the tricuspid valve. Diltiazem (2.2 x 10 -7 and 2.2 x 10 -6 M) had no effect on MDP of normal, Type I, or Type II cells. Diltiazem at 2.2 x 10 -6 M significantly reduced AP amplitude and V̇[max] of both Type I and normal cells. In contrast, even at 2.2 x 10 -7 M, diltiazem significantly reduced AP amplitude and V[max] of the Type II cells. Diltiazem, 2.2 x 10 -6 M, would often abolish AP of Type II cells, while Type I cells were more sensitive to tetrodotoxin. AP duration of normal cells was unaffected by diltiazem while that of Type I and II cells was significantly shortened.
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M3 - Article
VL - 4
SP - 986
EP - 993
JO - Journal of Cardiovascular Pharmacology
JF - Journal of Cardiovascular Pharmacology
SN - 0160-2446
IS - 6
ER -