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

Ca2+dependence of positive inotropic responses of guinea pig isolated cardiac preparations to cAMP-generating and cAMP-independent agonists

1984 ◽  
Vol 62 (1) ◽  
pp. 105-108 ◽  
Author(s):  
L. F. Yao ◽  
K. M. MacLeod ◽  
J. H. McNeill
Keyword(s):  
Guinea Pig ◽  
Papillary Muscles ◽  
Similar Magnitude ◽  
Myocardial Cells ◽  
Receptor Stimulation ◽  
Histamine Response ◽  
Β Receptor ◽  
Inotropic Responses ◽  
Stimulation Of

The effects of procedures which diminish Ca2+ influx into myocardial cells on responses of isolated cardiac preparations to cAMP-independent histamine H1 receptor stimulation and cAMP-generating β-receptor stimulation were measured. The histamine response of guinea pig left atria, which appears to be primarily mediated by H1 receptors, was depressed to a greater extent than was the response of this preparation to isoproterenol by decreasing the extracellular Ca2+ concentration, and by the Ca2+ influx blocker D-600. Similarly, while the H1 agonist 2-pyridylethylamine dihydrochloride (PEA) produced increases in tension of a similar magnitude as the partial β-agonist salbutamol in both left atria and in papillary muscles, responses of both preparations to PEA were depressed to a significantly greater extent by decreasing the extracellular Ca2+ concentration than were responses to salbutamol. Overall, both the basal developed force of papillary muscles and the responses of these preparations to H1 and β-receptor stimulation appeared to be less depressed by decreasing the extracellular Ca2+ concentration than were those of left atria. These results indicate that responses mediated via cAMP-independent H1 receptors, like those arising from α-receptor stimulation, are more sensitive to procedures which diminish Ca2+ influx than are responses arising from stimulation of cAMP-generating β-receptors. This may reflect differences in the mechanisms by which stimulation of H1, α-, and β-receptors give rise to positive inotropic responses. In addition, left atria may be more dependent than papillary muscles on extracellular Ca2+ for the support of contraction.

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.

Characterization of the inotropic response induced by stimulation of β-adrenergic and H1 histaminergic receptors in guinea pig left atria

1978 ◽  
Vol 56 (6) ◽  
pp. 926-933 ◽  
Author(s):  
Thomas E. Tenner Jr. ◽  
John H. McNeill
Keyword(s):  
Guinea Pig ◽  
Cardiac Muscle ◽  
Narrow Range ◽  
The Other ◽  
Inotropic Response ◽  
Receptor Stimulation ◽  
Experimental Conditions ◽  
High Frequencies ◽  
Stimulation Of

The inotropic response induced by β-adrenergic and H1 histaminergic receptor stimulation was characterized in guinea pig left atria by obtaining dose–response relationships for isoproterenol and histamine under various experimental conditions. Conditions (hypothermia, high frequencies of stimulation, and large extracellular calcium concentrations) which enhanced the ability of cardiac muscle to develop force also increased the sensitivity of the left atrium to isoproterenol while decreasing its efficacy. On the other hand, conditions which enhanced the ability of cardiac muscle to develop force depressed the efficacy of histamine to such an extent that the sensitivity to histamine was also decreased. In addition, conditions which markedly depressed the ability of cardiac muscle to develop force also decreased the efficacy and sensitivity to histamine. The data indicate that while β-adrenoceptor stimulation results in an inotropic response under all conditions studied, stimulation of H1 histaminergic receptors results in an inotropic response only within a narrow range of experimental conditions.

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 Serotonin increases L-type Ca2+ current and SR Ca2+ content through 5-HT4 receptors in failing rat ventricular cardiomyocytes

2007 ◽  
Vol 293 (4) ◽  
pp. H2367-H2376 ◽  
Author(s):  
Jon Arne Kro Birkeland ◽  
Fredrik Swift ◽  
Nils Tovsrud ◽  
Ulla Enger ◽  
Per Kristian Lunde ◽  
...  
Keyword(s):  
Myosin Light Chain ◽  
Troponin I ◽  
Contractile Function ◽  
Left Ventricular ◽  
Inotropic Response ◽  
Receptor Stimulation ◽  
Ventricular Cardiomyocytes ◽  
Myosin Light Chain 2 ◽  
Intracellular Ca ◽  
Male Wistar Rats

Rats with congestive heart failure (CHF) develop ventricular inotropic responsiveness to serotonin (5-HT), mediated through 5-HT2A and 5-HT4 receptors. Human ventricle is similarly responsive to 5-HT through 5-HT4 receptors. We studied isolated ventricular cardiomyocytes to clarify the effects of 5-HT on intracellular Ca2+ handling. Left-ventricular cardiomyocytes were isolated from male Wistar rats 6 wk after induction of postinfarction CHF. Contractile function and Ca2+ transients were measured in field-stimulated cardiomyocytes, and L-type Ca2+ current ( ICa,L) and sarcoplasmic reticulum (SR) Ca2+ content were measured in voltage-clamped cells. Protein phosphorylation was measured by Western blotting or phosphoprotein gel staining. 5-HT4- and 5-HT2A-receptor stimulation induced a positive inotropic response of 33 and 18% (both P < 0.05) and also increased the Ca2+ transient (44 and 6%, respectively; both P < 0.05). ICa,L and SR Ca2+ content increased only after 5-HT4-receptor stimulation (57 and 65%; both P < 0.05). Phospholamban serine16 (PLB-Ser16) and troponin I phosphorylation increased by 26 and 13% after 5-HT4-receptor stimulation ( P < 0.05). 5-HT2A-receptor stimulation increased the action potential duration and did not significantly change the phosphorylation of PLB-Ser16 or troponin I, but it increased myosin light chain 2 (MLC2) phosphorylation. In conclusion, the positive inotropic response to 5-HT4 stimulation results from increased ICa,L and increased phosphorylation of PLB-Ser16, which increases the SR Ca2+ content. 5-HT4 stimulation is thus, like β-adrenoceptor stimulation, possibly energetically unfavorable in CHF. 5-HT2A-receptor stimulation, previously studied in acute CHF, induces a positive inotropic response also in chronic CHF, probably mediated by MLC2 phosphorylation.

Muscarinic inhibition of ATP-sensitive K+ channels by protein kinase C in urinary bladder smooth muscle

1993 ◽  
Vol 265 (6) ◽  
pp. C1723-C1728 ◽  
Author(s):  
A. D. Bonev ◽  
M. T. Nelson
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Urinary Bladder ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Katp Channels ◽  
Muscle Cells ◽  
Receptor Stimulation ◽  
Kinase C

We explored the possibility that muscarinic receptor stimulation can inhibit ATP-sensitive K+ (KATP) channels in smooth muscle cells from guinea pig urinary bladder. Whole cell K+ currents were measured in smooth muscle cells isolated from the detrusor muscle of the guinea pig bladder. Stimulation of muscarinic receptors by carbachol (CCh; 10 microM) inhibited KATP currents by 60.7%. Guanosine 5'-O-(2-thiodiphosphate) in the pipette (internal) solution prevented the CCh-induced inhibition of KATP currents. Activators of protein kinase C (PKC), a diacylglycerol analogue, and phorbol 12-myristate 13-acetate inhibited KATP currents by 63.5 and 73.9%, respectively. Blockers of PKC (bisindolylmaleimide GF-109203X and calphostin C) greatly reduced CCh inhibition of KATP currents. We propose that muscarinic receptor stimulation inhibits KATP channels in smooth muscle cells from urinary bladder through activation of PKC.

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