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Cardiovascular effects of human and rat CGRP compared in the rat and other species
Insights
Human and rat calcitonin gene-related peptide (CGRP) directly impact the cardiovascular system, lowering blood pressure and altering heart rate in animal models. Their effects were largely consistent across different species and tissues.
Area of Science:
- Cardiovascular Pharmacology
- Neuropeptide Research
Background:
- Calcitonin gene-related peptide (CGRP) is a neuropeptide with known cardiovascular effects.
- Human and rat CGRP sequences differ slightly, raising questions about potential functional variations.
Purpose of the Study:
- To compare the cardiovascular effects of human and rat CGRP.
- To investigate the direct actions of CGRP on the cardiovascular system.
Main Methods:
- Intravenous administration of human and rat CGRP in anesthetized rats.
- Perfusion of isolated rat and rabbit hearts with CGRP.
- Assessment of CGRP effects on isolated rat and guinea-pig atria.
Main Results:
- Both human and rat CGRP lowered blood pressure and increased heart rate in vivo.
- CGRP decreased coronary perfusion pressure and caused tachycardia in isolated rat hearts.
- Human CGRP increased coronary flow in isolated rabbit hearts.
- Both peptides increased atrial rate and force, with rat CGRP showing differential potency in guinea-pig atria.
Conclusions:
- Human and rat CGRP exert direct, qualitatively similar effects on the cardiovascular system.
- Pharmacological interventions did not significantly alter CGRP's cardiovascular actions.
- Species-specific differences in CGRP's chronotropic and inotropic effects were observed in isolated atria.
Abstract:
In the anaesthetised rat, human and rat CGRP (calcitonin gene-related peptide) which differ by 4 out of 37 amino acids, when given intravenously, lowered blood pressure and increased heart rate. The effects of human CGRP were unaltered by either propranolol or by mepyramine plus cimetidine. In the rat isolated perfused heart the peptides decreased coronary perfusion pressure and evoked a tachycardia. The latter effect was not seen in the rabbit isolated heart, although human CGRP increased coronary flow. The two peptides were equipotent at increasing the rate and force of contraction in the rat isolated right atrium, effects unaltered by propranolol. In the guinea-pig isolated atrium, rat CGRP was 10 times as potent as a chronotropic agent than as an inotrope, unlike human CGRP which was equipotent. In conclusion, human and rat CGRP probably acted directly on the cardiovascular system to produce their qualitatively similar effects.