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Sympathetic efferent activity in the viscerovascular reflexes induced by urinary bladder distension. Jpn J Physiol 1995;45(2):265-77

Date

01/01/1995

Pubmed ID

7563963

DOI

10.2170/jjphysiol.45.265

Scopus ID

2-s2.0-0029164202 (requires institutional sign-in at Scopus site)   9 Citations

Abstract

In chloralose-anesthetized cats, rapid distension of the urinary bladder with warm (37 degrees C) normal saline (50-60 ml) causes an increase in blood pressure and contraction of the spleen. This response is due to peripheral vasoconstriction. In this experiment, the evidence of direct involvement of the spleen, as well as splenic and splanchnic sympathetic efferent activity on the viscerovascular reflexes, was investigated by pharmacological and electrophysiological (single unit preparation) means and analysis. The viscerovascular reflexes induced by urinary bladder distension remained unaffected by propranolol, but phentolamine, guanethidine sulfate, and hexamethonium completely antagonized the reflex vasopressor response. All these results with these blocking agents show that sympathetic nerves are actively involved in the reflex responses to distension of the urinary bladder with activation at the postganglionic level involving alpha-adrenoceptors and thereby the release of catecholamines. It is thus evident that the same mechanisms operate in the case of reflex elevation of blood pressure and contraction of the spleen. After bilateral denervation of the splanchnic sympathetic nerves, bladder distension failed to produce a reflex response. The efferent activity from the splanchnic and splenic sympathetic nerves in producing a reflex rise in blood pressure was recorded for direct evidence. The significant increase of asynchronous spontaneous discharge rate in the splanchnic and splenic sympathetic nerves was found along with a rise in blood pressure during bladder distension. On the basis of this study, it may be suggested that the spleen as well as splenic and splanchnic sympathetic nerves play an important role in the control of viscerovascular reflexes.

Author List

Medda BK, Koley J, Koley B

Author

Bidyut K. Medda PhD Associate Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Blood Pressure
Cats
Efferent Pathways
Female
Guanethidine
Hexamethonium
Male
Phentolamine
Propranolol
Reflex
Reserpine
Splanchnic Nerves
Spleen
Sympathectomy
Sympathetic Nervous System
Urinary Bladder
Viscera