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Chronotropic effects (from chrono-, meaning time, and tropos, "a turn") are those that change the heart rate. Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the nerves that influence it, such as by changing the rhythm produced by the sinoatrial node. Positive chronotropes ...
A cardiac stimulant is a drug which acts as a stimulant of the heart – e.g., via positive chronotropic action (increased heart rate) and/or inotropic action (increased myocardial contractility). They increase cardiac output (the amount of blood pumped by the heart over time).
Epinephrine (adrenaline). Activation of β 1 receptors induces positive inotropic, chronotropic output of the cardiac muscle, leading to increased heart rate and blood pressure, secretion of ghrelin from the stomach, and renin release from the kidneys.
Positive chronotropic, dromotropic and inotropic effects, ... It is a presynaptic receptor, causing negative feedback on, for example, norepinephrine (NE).
Beta-blockade of the β 1 receptor will inhibit cAMP from phosphorylating, and it will decrease the ionotrophic and chronotropic effect. Note that drugs may be cardioselective, or act on β 1 receptors in the heart only, but still have intrinsic sympathomimetic activity.
β 1-Adrenergic receptor agonists, also known as beta-1 agonists, are a class of drugs that bind selectively to the β 1-adrenergic receptor.As a result, they act more selectively upon the heart. β-Adrenoceptors typically bind to norepinephrine release by sympathetic adrenergic nerves and to circulating epinephrine.
The Bainbridge reflex is the predominant, [16] [17] but not the only mechanism mediating increases in heart rate in response to increased atrial stretch: stretching of the pacemaker cells of the sinoatrial node has a direct positive chronotropic effect on the rate of the sinoatrial node. [18]
Isoprenaline has positive inotropic and chronotropic effects on the heart. β 2-Adrenergic receptor stimulation in arteriolar smooth muscle induces vasodilation. Its inotropic and chronotropic effects elevate systolic blood pressure, while its vasodilatory effects tend to lower diastolic blood pressure.