Pressor and tachycardic responses to intravenous substance P in anesthetized rats.
Intravenous injection of 3-33 nmol/kg of substance P (SP) caused pressor and tachycardic responses in anesthetized rats. The responses were not blocked by a ganglion nicotinic receptor antagonist or by pithing. Pretreatment with reserpine blocked both responses. beta-Adrenoceptor blockade attenuated only the tachycardic response, and alpha-adrenoceptor blockade attenuated only the pressor response. These findings indicated that the effects of SP to increase blood pressure and heart rate are due to sympathetic ganglion stimulation. Studies with adrenalectomized rats showed that stimulation of the adrenals by SP contributes to both responses but makes a greater contribution to the tachycardic response. These observations raise the possibility that the tachykinin innervation of sympathetic ganglia and the adrenal medulla may be involved in the local regulation of blood pressure and heart rate.
Hancock
J C
JC
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614, USA.
Lindsay
G W
GW
D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D003714:Denervation; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007275:Injections, Intravenous; D008297:Male; D018733:Nicotinic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012110:Reserpine / Q000494:pharmacology; D013373:Substance P / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D013610:Tachycardia / Q000139:chemically induced* / Q000503:physiopathology
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D005730:Ganglionic Blockers; D018733:Nicotinic Antagonists; D013373:Substance P; D012110:Reserpine