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Inhibition of cardiac vagal action by galanin but not neuropeptide Y in the brush‐tailed possum Trichosurus vulpecula.
Author(s) -
Courtice G P,
Potter E K,
McCloskey D I
Publication year - 1993
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1993.sp019518
Subject(s) - galanin , medicine , endocrinology , neuropeptide , blood pressure , neuropeptide y receptor , vagus nerve , pressor response , stimulation , heart rate , chemistry , receptor
1. Stimulation of the right cardiac sympathetic nerve for 2 min at 16 Hz in the presence of either beta‐ or alpha‐ and beta‐adrenoceptor blockade evoked attenuation of cardiac vagal action in eight possums: 31.3 +/‐ 10.3% maximum inhibition of cardiac vagal action on prolonging pulse interval, with a time to half‐recovery of 4.9 +/‐ 1.1 min. 2. Intravenous injection of galanin (2‐3.5 nmol kg‐1) evoked similar inhibition of cardiac vagal action: 41.3 +/‐ 4.1% maximum inhibition of cardiac vagal action on pulse interval, with a time to half‐recovery of 13.4 +/‐ 2.3 min. 3. Intravenous injection of neuropeptide Y (NPY) at greater molar doses (6.5‐10 nmol kg‐1) caused no inhibition of cardiac vagal action. 4. The galanin injections caused a powerful pressor response: 57.1 +/‐ 4.9 mmHg increase in systolic blood pressure. NPY caused a smaller pressor response, despite administration of higher molar doses: 36.7 +/‐ 3.0 mmHg increase in systolic blood pressure. 5. In the possum, galanin but not NPY can mimic the effects of cardiac sympathetic nerve stimulation on vagal action. Galanin also causes large pressor effects.