Effects of sodium pentobarbital on electric and mechanical activities of guinea pig papillary muscle.
OBJECTIVE
To study the effects of sodium pentobarbital (SP) on the action potential (AP) and contraction of guinea pig papillary muscle.


METHODS
Using conventional glass microelectrode and mechanical recording of myocardium contraction.


RESULTS
SP (> or = 10 mumol.L-1) prolonged the AP duration (APD) and effective refractory period (ERP), while amplitude (APA) and Vmax of phase 0 showed no changes. The effects of SP were abolished by pretreatment with cromakalim, an agonist of ATP-sensitive K+ channel. The maximal isometric tension (Pmax) and velocity of tension development (dT/dt) were decreased to 51% and 48% of control, respectively. The first postrest beat (B1) and second postrest beat (B2) were also depressed.


CONCLUSIONS
SP affected the action potential by reducing activities of the K+ channels and reduced the contraction of guinea pig myocardium.
Zhang
Y
Y
Department of Physiology, Hebei Medical University, Shijiazhuang, China.
Gu
S Z
SZ
Hao
Y C
YC
Song
L L
LL
Guo
S M
SM
Lu
S G
SG
D000200:Action Potentials / Q000187:drug effects; D000759:Adjuvants, Anesthesia / Q000009:adverse effects*; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects; D010424:Pentobarbital / Q000009:adverse effects*
D000759:Adjuvants, Anesthesia; D010424:Pentobarbital