FRANK M. SMITH, Ph.D.
E-mail: F.M.Smith@Dal.Ca

Autonomic Control of the Circulation

The role of the autonomic nervous system in regulating the mammalian circulation is being investigated at the whole-animal level in in vivo experiments, and at the level of individual neurons in in vitro experiments. In recent studies of the neurons in mammalian intracardiac ganglia, we have found evidence of afferent and "local circuit" as well as efferent neurons. Intraganglionic neurotransmission involves peptidergic , aminergic , peptidergic and purinergic neurotransmitters as well as acetylcholine. The role of these neurotransmitters in neural control of the heart is under investigation. We are characterizing the physiological, morphological and pharmacological properties of intracardiac neurons, using both in vivo intracellular techniques in studies of neural preparations from mammalian hearts.

Research Support
Medical Research Council of Canada
Canadian Heart and Stroke Foundation

Publications
Smith, F.M., D.A. Hopkins and J.A. Armour (1992) Electrophysiological properties of in vitro intrinsic cardiac neurons in the pig ( Sus scrofa ). Brain Res. Bull. 28:715-725.

Armour , J.A., Huang, M.H. and Smith, F.M. (1993) Peptidergic modulation of canine intrinsic cardiac neurons. Peptides 14:191-202.

Huang, M.H., Smith, F.M. and Armour , J.A. (1993) Modulation of canine intrinsic cardiac neuronal activity by nicotinic, muscarinic and á -adrenergic agonists. Am. J. Physiol . 264:H1275-H1282.

Huang, M.H., Smith, F.M. and Armour , J.A. (1993) Amino acids modify the activity of canine intrinsic cardiac neurons involved in cardiac regulation. Am. J. Physiol . 264:H1275-1282.

Armour , J.A., Smith, F.M., Losier , A.M., Ellenberger, H.H. and Hopkins, D.A. (1995) Modulation of intrinsic cardiac neuronal activity by nitricoxide donors induces cardiodynamic changes. Am. J. Physiol . 268:R403-R413.

Smith, F. M. 1999 Extrinsic inputs to intrinsic neurons of the porcine heart in vitro . Am. J. Physiol . 276:R455-R467.

Leger, J., Croll , R. P. and Smith, F. M. 1999 Regional distribution of extrinsic innervation of intrinsic cardiac neurons in the guinea pig. J. Comp. Neurol . 407:303-317.