Ontogeny of cholinergic and adrenergic cardiovascular regulation in the domestic chicken (Gallus gallus)

Abstract

Adrenergic and cholinergic tone on the cardiovascular system of embryonic chickens was determined during days 12, 15, 19, 20, and 21 of development. Administration of the muscarinic antagonist atropine (1 mg/kg) resulted in no significant change in heart rate or arterial pressure at any developmental age. In addition, the general cardiovascular depressive effects of hypoxia were unaltered by pretreatment with atropine. In addition, the ganglionic blocking agent hexamethonium (25 mg/kg) did not induce changes in heart rate. The beta-adrenergic antagonist propranolol (3 mg/kg) induced a bradycardia of similar magnitude on all days studied, with a transient hypertensive action on days 19-20, indicating the existence of an important cardiac and vascular beta-adrenergic tone. Injections of the alpha-adrenergic antagonists prazosin or phentolamine (1 mg/kg) reduced arterial pressure significantly on all days of incubation studied. Collectively, the data indicate that embryonic chickens rely primarily on adrenergic control of cardiovascular function, with no contribution from the parasympathetic nervous system.

Effect of Acute Hypoxia on the Motor Activity and Heart Rate of the 10- and 14-Day Chick Embryo

“…Some authors believe that the parasympathetic control already exists as early as D14 [47,48]. Others assume that parasympathetic control of the HR does not appear till end of embryogenesis [49]. The formation of tonic parasympathetic influence on the HR is incomplete at the ontogenetic stage dealt with in our study; however, it may already be expressed in a response to hypoxia on D14.…”

The phylogeny and ontogeny of autonomic control of the heart and cardiorespiratory interactions in vertebrates

“…4), but measurements of blood flow have only been conducted in embryonic alligators (Eme et al, 2011a). Embryonic heart mass has been suggested to be an index of stroke volume during reptilian development (Birchard and Reiber, 1996;Crossley and Altimiras, 2000) so that changes in heart mass, in combination with measurement of f H , may provide an index of the changes in cardiac output accompanying development, enabling study of its control.…”

“…5). This excitatory tone is derived primarily from humoral control, as a result of high levels of circulating catecholamines in embryonic chickens and possibly other species (Crossley and Altimiras, 2000). Although cardiac muscarinic and adrenergic receptors are found in embryonic chickens during the first quarter of incubation (Barry, 1950), and the mechanisms for production and degradation of ACh and noradrenaline are also present during this time (Zacks, 1954;Ignarro and Shideman, 1968), the inhibitory vagal control of f H is absent until close to hatching in some species (Table 2; Fig.…”

Physiological Society Symposium — Vagal Control: From Axolotl to Man

“…In the snapping turtle (Chelydru serpentina) heart rate fell slightly before, and markedly after, hatching indicating the establishment of a vagal tone on the heart, coincident with the onset of lung breathing (Birchard & Reiber, 1996). In contrast, the developing chick showed no indication of a cardiac vagal tone right up to first breaking through the shell, prior to hatching; though a /3-adrenergic tonus on the heart was apparent from an early stage of development (Crossley & Altimiras, 2000). The study of the oviparousamphibians, reptiles and birds is likely to improve our understanding of the development (Crossley & Altimiras, 2000) and evolution of central control of cardiorespiratory interactions.…”