| dc.contributor.author | Leger, James Paul. | en_US |
| dc.date.accessioned | 2014-10-21T12:33:49Z | |
| dc.date.available | 1999 | |
| dc.date.issued | 1999 | en_US |
| dc.identifier.other | AAINQ49274 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55655 | |
| dc.description | Neurons within the mammalian heart are connected into a neural network which functions in regional and global control of cardiodynamics. There is anatomical and functional evidence for the presence of adrenergic terminals surrounding some intracardiac neurons but the function of these terminals is not clear. The focus of this thesis is to investigate the anatomical distribution of adrenergic elements within the intracardiac -nervous system, and determining the influence of adrenergic agents on neurotransmission in this system in the guinea-pig heart. Immunohistochemical processing for tyrosine hydroxylase (TH) and histochemistry for aldehyde-induced fluorescence showed that no neuronal somata contained TH or detectable levels of amines. Amine-containing terminals and small cells (less than 11 mum diameter) were found throughout the atria; many of these elements were associated with ganglionic neurons. The presence of adrenergic terminals in intracardiac ganglia is hypothesized to represent potential sites for adrenergic modulation of ganglionic neurotransmission. | en_US |
| dc.description | To evaluate the effects of adrenergic agents on ganglionic neurotransmission, an in vitro preparation of guinea-pig atria including attached extrinsic innervation was developed and its viability confirmed. This preparation was then used in intracellular electrophysiological studies of the properties of intracardiac neurons and the influence of adrenergic agents on these properties. Local application of the alpha-adrenergic agonist phenylephrine or the beta-adrenergic agonist isoproteronol modified properties of some intracardaic neurons, and both agonists were capable of facilitating or inhibiting neurotransmission to these neurons. These effects were blocked by the alpha- and beta-adrenoceptor specific antagonists prazosin and timolol, respectively. These studies suggest that endogenous catecholamines, released from adrenergic nerve terminals within' intracardiac ganglia, can have powerful effects on the functions of individual neurons in these ganglia. Taken together, the results of the studies in this thesis provide evidence of an anatomical and physiological substrate for potential modulation of intracardiac ganglionic neurotransmission by the sympathetic nervous system. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1999. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Anatomy. | en_US |
| dc.title | Adrenergic modulation of neurotransmission in the intracardiac nervous system of the guinea-pig. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
