Decreased sensitivity to beta-adrenergic stimulation of the ventricular cells isolated from the spontaneously hypertensive rat heart.
1. The stimulatory effects of isoproterenol on the L-type Ca2+ current (ICa) were compared between the control (WKY) and hypertensive (SHR) rat heart cells, using the patch-clamp method. 2. The current density and the shape of the current-voltage relationship for ICa were not different between the two groups. However, the maximal percentage increase in response to isoproterenol was smaller in SHR (+91% in SHR and +81% in WKY), and the ED50 was significantly higher in SHR (0.081 mu mol/L in SHR and 0.020 mu mol/L in WKY). IBMX, a potent phosphodiesterase inhibitor, significantly increased the isoproterenol-stimulated ICa in SHR, but not in WKY. These results suggest an impaired cAMP production in SHR heart cells.
Habuchi
Y
Y
Department of Clinical Laboratory and Medicine, Kyoto Prefectural University of Medicine, Kawaramachi, Japan.
Lu
L L
LL
Okamoto
S
S
Komori
T
T
Takahashi
H
H
Morikawa
J
J
Yoshimura
M
M
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D006321:Heart / Q000187:drug effects*; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000318:Adrenergic beta-Agonists; D015220:Calcium Channels; D010726:Phosphodiesterase Inhibitors; D007545:Isoproterenol; D015056:1-Methyl-3-isobutylxanthine