TY - JOUR
T1 - Inotropic response of rabbit ventricular myocytes to endothelin-1
T2 - Difference from isolated papillary muscles
AU - Talukder, M. A.Hassan
AU - Norota, Ikuo
AU - Sakurai, Kiyoharu
AU - Endoh, Masao
PY - 2001
Y1 - 2001
N2 - Endothelin-1 (ET-1) increased cell shortening and Ca2+ transients over the concentration of 3 × 10-11 M to 10-9 M with EC50 of 8.3 × 10-11 M in rabbit single ventricular myocytes. Thus ET-1 was approximately 60 times more potent in single myocytes than in papillary muscles (EC50 = 5.1 × 10-9 M) of the same species. In single myocytes, ET-1 at 10-8 M elicited an inhibitory response that counteracted the facilitatory response: the concentration-response curve (CRC) for ET-1 was bell shaped. The ETA-receptor antagonist BQ-485 shifted CRC for ET-1 to the right in parallel; however, the facilitatory response to 10-8 M ET-1 was markedly enhanced by BQ-485 and also by the ETB antagonist BQ-788. The ETA/ETB antagonist TAK-044 abolished the ET-1-induced response. These findings indicate that the response to ET-1 of single myocytes is different from that of papillary muscles in concentration dependence, characteristics of the response, and susceptibility to ET-receptor antagonists. Anomalous pharmacological characteristics of ET-1-induced response in rabbit papillary muscles may be due to integrated regulatory mechanisms that may involve also various types of noncardiac cell in ventricular myocardium.
AB - Endothelin-1 (ET-1) increased cell shortening and Ca2+ transients over the concentration of 3 × 10-11 M to 10-9 M with EC50 of 8.3 × 10-11 M in rabbit single ventricular myocytes. Thus ET-1 was approximately 60 times more potent in single myocytes than in papillary muscles (EC50 = 5.1 × 10-9 M) of the same species. In single myocytes, ET-1 at 10-8 M elicited an inhibitory response that counteracted the facilitatory response: the concentration-response curve (CRC) for ET-1 was bell shaped. The ETA-receptor antagonist BQ-485 shifted CRC for ET-1 to the right in parallel; however, the facilitatory response to 10-8 M ET-1 was markedly enhanced by BQ-485 and also by the ETB antagonist BQ-788. The ETA/ETB antagonist TAK-044 abolished the ET-1-induced response. These findings indicate that the response to ET-1 of single myocytes is different from that of papillary muscles in concentration dependence, characteristics of the response, and susceptibility to ET-receptor antagonists. Anomalous pharmacological characteristics of ET-1-induced response in rabbit papillary muscles may be due to integrated regulatory mechanisms that may involve also various types of noncardiac cell in ventricular myocardium.
UR - http://www.scopus.com/inward/record.url?scp=0034880756&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034880756&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.2001.281.2.h596
DO - 10.1152/ajpheart.2001.281.2.h596
M3 - Article
C2 - 11454562
AN - SCOPUS:0034880756
SN - 0363-6135
VL - 281
SP - H596-H605
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 2 50-2
ER -