scholarly journals A Xanthine Derivative Denbufylline Inhibits Negative Inotropic Response to Verapamil in Guinea Pig Ventricular Papillary Muscles, Independent of Its Phosphodiesterase Inhibitory Activity

1995 ◽  
Vol 69 (3) ◽  
pp. 277-279
Author(s):  
Fujiko Sanae ◽  
Shinji Ohmae ◽  
Kenzo Takagi ◽  
Ken-ichi Miyamoto
Keyword(s):  
Guinea Pig ◽  
Inhibitory Activity ◽  
Papillary Muscles ◽  
Inotropic Response ◽  
Xanthine Derivative ◽  
Negative Inotropic Response

Does endogenous adenosine have a role in the cardiac responses to isoprenaline and in the rapid fade of the inotropic response of perfused heart?

1994 ◽  
Vol 72 (2) ◽  
pp. 152-160 ◽  
Author(s):  
Kenneth J. Broadley ◽  
Andrew N. A. Wilson
Keyword(s):  
Guinea Pig ◽  
Adenosine Deaminase ◽  
Papillary Muscles ◽  
Inotropic Response ◽  
Force Of Contraction ◽  
Depressant Effect ◽  
Response Curves ◽  
Endogenous Adenosine ◽  
Left And Right ◽  
Right Atria

The role of endogenous adenosine during the β-adrenoceptor responses to isoprenaline of guinea-pig isolated cardiac preparations was examined. Insignificant effects of adenosine deaminase (0.3 U∙mL−1) on cumulative concentration–response curves for isoprenaline on isolated left and right atria and papillary muscles indicated a negligible depressant effect of endogenous adenosine during these responses. The increase in force of contraction to an infusion of isoprenaline (14 nM) in perfused spontaneously beating hearts rapidly waned while the infusion continued, whereas the increase in rate of contraction remained constant throughout the infusion. The degree of fade was less in paced preparations (5 Hz), indicating that it was only in part due to the rate increase exerting some mechanical constraint on the force of contraction. The P1-purinoceptor antagonist 8-phenyltheophylline (12 μM) and adenosine deaminase (0.3 U∙mL−1) did not enhance the peak responses to the isoprenaline infusion. The fade of the inotropic response in both spontaneous and paced hearts was also not attenuated by the presence of 8-phenyltheophylline or adenosine deaminase. The fade was not, therefore, due to release of endogenous adenosine exerting a depressant effect. Whether this declining inotropic response represents a form of rapid desensitization remains to be determined.Key words: guinea-pig perfused hearts, left and right atria, papillary muscles, β-adrenoceptor agonist, endogenous adenosine.

scholarly journals Vasopressin V1-Receptor Stimulation Produces a Positive Inotropic Response without Affecting pHi in Guinea Pig Papillary Muscles

1995 ◽  
Vol 68 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Hiroshi Yamaguchi ◽  
Hiroko Uemura ◽  
Toshihiro Saito ◽  
Yoshiaki Masuda ◽  
Haruaki Nakaya
Keyword(s):  
Guinea Pig ◽  
Papillary Muscles ◽  
Inotropic Response ◽  
Receptor Stimulation

Characterization of responses to neurokinin A in the isolated perfused guinea pig heart

1998 ◽  
Vol 275 (6) ◽  
pp. R1803-R1811 ◽  
Author(s):  
Donald B. Hoover ◽  
Yingzi Chang ◽  
John C. Hancock
Keyword(s):  
Guinea Pig ◽  
Perfusion Pressure ◽  
Specific Binding ◽  
Neurokinin A ◽  
Inotropic Response ◽  
Guinea Pig Heart ◽  
Specific Binding Sites ◽  
Negative Inotropic Response ◽  
Percent Decrease

Goals of this study were to identify and characterize effects of neurokinin A (NKA) in isolated guinea pig hearts. Bradycardia, augmentation of ventricular contractions, and reduction of perfusion pressure were prominent responses to bolus injections of NKA (0.25–25 nmol). NKA was more potent than substance P (SP) in causing bradycardia but did not differ in potency for lowering perfusion pressure. Doses of SP of 25 nmol or less decreased ventricular force, whereas 100 nmol caused a biphasic response. The percent decrease in heart rate produced by 25 nmol NKA was reduced from 58.0 ± 4.8 to 39.6 ± 3.5% in the presence of 1 μM atropine ( n = 5). The positive inotropic response to 25 nmol of NKA in spontaneously beating hearts was replaced by a negative inotropic response during pacing (22.5 ± 3.3% increase vs. 11.7 ± 1.7% decrease, n = 5). Reserpine pretreatment did not affect the positive inotropic response to NKA. Specific binding sites for 125I-labeled NKA were localized to intracardiac ganglia and coronary arteries but not to myocardium. It was concluded that 1) negative chronotropic responses to NKA involve cholinergic and noncholinergic mechanisms, and 2) the positive inotropic response is an indirect action.

Effects of zinc on cardiac muscle contraction

1965 ◽  
Vol 209 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Winifred G. Nayler ◽  
Juliet E. Anderson
Keyword(s):  
Skeletal Muscle ◽  
Action Potential ◽  
Cardiac Muscle ◽  
Papillary Muscles ◽  
Ventricular Muscle ◽  
Inotropic Response ◽  
Prolonged Action ◽  
Rat Hearts ◽  
Negative Inotropic Response ◽  
Isolated Rat

The effect of 0.001–5 mm Zn++ on the contractions of dog, rabbit, and monkey papillary muscles, rat atria, isolated rat hearts, and toad and tortoise ventricular muscle was investigated. Zn++ depressed the contractions of all cardiac muscle preparations tested; the negative inotropic response was associated with an unchanged duration of contraction and a prolonged action potential. Zn++ > 0.5 mm caused mechanical arrest; perfusion of Zn++-arrested amphibian preparations with 100 mm K+ solution resulted in contractures equal in magnitude to that evoked by similar perfusion with 100 mm K+ in the absence of Zn++. It is concluded that the action of Zn++ on cardiac muscle differs essentially from that described for skeletal muscle.

Electromechanical Effects of bPTH-(1-34) on Rabbit Sinus Node Cells and Guinea Pig Papillary Muscles

1988 ◽  
Vol 11 (5) ◽  
pp. 619-625 ◽  
Author(s):  
Noriaki Kondo ◽  
Shoji Shibata ◽  
Thomas E. Tenner ◽  
Peter K. Pang
Keyword(s):  
Guinea Pig ◽  
Sinus Node ◽  
Papillary Muscles ◽  
Electromechanical Effects

scholarly journals Inhibitory activity of the novel CB2 receptor agonist, GW833972A, on guinea-pig and human sensory nerve function in the airways

2008 ◽  
Vol 155 (4) ◽  
pp. 547-557 ◽  
Author(s):  
M G Belvisi ◽  
H J Patel ◽  
V Freund-Michel ◽  
D J Hele ◽  
N Crispino ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Inhibitory Activity ◽  
Receptor Agonist ◽  
Sensory Nerve ◽  
The Novel ◽  
Nerve Function ◽  
Cb2 Receptor
Sign in / Sign up

Export Citation Format

Share Document