A device for measuring myocardial contractility

Goodman, A. H.; Angus, James A.; Einstein, Rosemarie; Cobbin, L. B.

doi:10.1007/bf02474196

Cited by 16 publications

(10 citation statements)

References 6 publications

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“…Their results may also have been influenced by anaesthesia since, in unanaesthetized rabbits, a fall in LV dP/dt was seen after NPY administration (Minson et al, 1987). The index of contractility used in the present experiments is less influenced by alterations in afterload (Goodman et al, 1972) and thus more accurately reflects changes in the inotropic state of the heart.…”

Section: Discussionmentioning

confidence: 77%

“…The first derivative of the rising phase of LVP, dP/dt, was obtained by an active differentiating circuit. The index of contractility used in this study, (dP/dt)/IIT (Goodman et al, 1972), was obtained by the division of maximum dP/dt by the time integral of isovolumic ventricular pressure (integrated isometric tension) during the period from the R-wave of the ECG to the peak dP/dt. The index was computed, beat-bybeat, by an on-line digital computer (PDP 11/34,Digital Equipment,Australia (Levy et al, 1966).…”

Section: Introductionmentioning

confidence: 99%

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The effects of neuropeptide Y on myocardial contractility and coronary blood flow

Awad

Einstein

Potter

et al. 1991

British J Pharmacology

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1 This study was designed to assess the effects of exogenous neuropeptide Y (NPY) on cardiac contractility and coronary blood flow (CBF) in anaesthetized dogs and to evaluate the effect of NPY on the responses to sympathetic and parasympathetic stimulation and to inotropic agents.2 Bolus doses of NPY (500.ug), administered via the femoral vein, increased mean arterial pressure. The pressor effect was associated with reductions in heart rate, CBF and cardiac contractility. 3 The effects of NPY (500pug) on contractility and CBF were compared with that of vasopressin (VP) (1 unit). For similar reductions in CBF, NPY and VP had similar negative inotropic effects. Thus, it is likely that the negative inotropic response to NPY is not due to a direct effect of NPY on the heart muscle but is largely due to coronary vasoconstriction. 4 In the presence of NPY (500,pg, i.v.), there was an inhibition of the positive inotropic response to stimulation of the left cardiac sympathetic nerve (2 or 5Hz, 0.05 ms). NPY also inhibited the negative inotropic response and chronotropic response to vagal stimulation (2, 3 or 5 Hz, 0.05 ms). 5 Dose-response curves were obtained for the inotropic, chronotropic and pressor responses to cumulative infusions of noradrenaline (n = 6) and dobutamine (n = 6). NPY had no effect on these dose-response curves.6 The effect of NPY on the responses to salbutamol and impromidine was assessed. NPY did not alter the positive inotropic, chronotropic or depressor responses to these agonists. 7 Our results indicate that NPY has direct, postsynaptic vasoconstrictor activity and the reduction in myocardial contractility and heart rate are due to a combination of coronary vasoconstriction, baroreceptor reflex activation and presynaptic inhibition of transmitter release from sympathetic nerves. The welldocumented inhibitory effect of NPY on the chronotropic response to parasympathetic stimulation was confirmed and similar inhibition of the inotropic response to both sympathetic and parasympathetic stimulation was demonstrated. Since there was no modulation of the inotropic effects of exogenous a-and a1-adrenoceptor or H2-receptor agonists, it is concluded that the effects of NPY on myocardial contractility are exerted presynaptically.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

The effects of neuropeptide Y on myocardial contractility and coronary blood flow

Awad

Einstein

Potter

et al. 1991

British J Pharmacology

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“…In order to abolish brain and spinal cord activity 10 ml of ethanol was injected into the cisterna magna (Goodman, Einstein & Granger, 1978). Systemic blood pressure (BP), heart rate (HR) and myocardial contractility (MC: -) (Goodman et al, 1972) were continuously monitored.…”

Section: Gastric and Intestinalmentioning

confidence: 99%

“…Using an elegant open-chest anaesthetized dog preparation (Goodman et al, 1972) DT-0-Glu (0.056 pmol/kg) produced a peak inotropic response at 45 min following a 15 min i.v. infusion as compared to a similar peak effect at 90 min following 0.112 pmol/kg digoxin.…”

Section: Study Of the Acute Toxicity Kinetics And Pharmacological Acmentioning

confidence: 99%

Proceedings of the Australasian Society of Clinical and Experimental Pharmacologists

1983

Clin Exp Pharma Physio

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“…The index of contractility used in this study was obtained by the division of maximum dP/dt by the time integral of isovolumic ventricular pressure during the period from the R-wave of the ECG to the peak dP/dt (Goodman et al, 1972). The index was computed, beat-by-beat, by an on-line digital computer (PDP 11/34, Digital Equipment Australia).…”

Section: Methodsmentioning

confidence: 99%

Positive inotropic effects of histamine in anaesthetized dogs

Einstein

Mihailidou

Richardson

1987

British J Pharmacology

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1 The cardiovascular effects of histamine were examined in dogs anaesthetized with pentobarbitone 2 The effect of histamine on heart rate, blood pressure, left ventricular pressure, dP/dt,,,nv, and dP/dt: IIT (integrated isometric tension) was compared in the presence and absence ofautonomic reflexes and blood pressure control. 3 In innervated animals with no attempt to control blood pressure, histamine produced dosedependent decreases in blood pressure and heart rate and either positive or negative inotropic actions. 4 When autonomic reflexes were abolished, this variability in inotropic response was reduced and histamine produced a slight positive inotropic response. There was a decrease in blood pressure and a positive chronotropic response to histamine. 5 When blood pressure was controlled and the cardiac nerves were intact, histamine produced a decrease in heart rate. However, in the denervated animals, there was a slight increase in heart rate. 6 Inotropic responses to histamine in the blood pressure controlled groups were less variable than when blood pressure was uncontrolled. In all of these animals there was an increase in contractility, the increase being more marked in the denervated group. 7 The H2-receptor agonist impromidine produced a positive inotropic action in intact animals with uncontrolled blood pressure.

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A device for measuring myocardial contractility

Cited by 16 publications

References 6 publications

The effects of neuropeptide Y on myocardial contractility and coronary blood flow

The effects of neuropeptide Y on myocardial contractility and coronary blood flow

Proceedings of the Australasian Society of Clinical and Experimental Pharmacologists

Positive inotropic effects of histamine in anaesthetized dogs

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