Rhythmic contractions of the teat sphincter in bovines: an expulsion mechanism
- 1 March 1982
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
- Vol. 242 (3), R181-R184
- https://doi.org/10.1152/ajpregu.1982.242.3.r181
Abstract
Spontaneous and induced rhythmic contractions of the teat sphincter muscle were measured in conscious bovines using a pressure transponding device. Contractions were induced or the frequency of contractions was increased by intravenous injection of phenylephrine. Epinephrine, isoxsuprine, and phentolamine inhibited contractions and prior administration of phentolamine blocked the response to phenylephrine. Contractions in adjacent teats were asyncronous and the frequency of spontaneous contractions (0-20/min) increased with time after milking, presumably due to the effect of the increased muscle tension that resulted from the accumulation of milk within the gland cistern and the teat cistern. Furthermore, the contractions were found to be peristaltic in nature. Squeezing the tip of the teat was found to induce one or more contractions, whereas squeezing the teat elsewhere had no effect. It was hypothesized that peristaltic contractions in response to irritation of the tip of the teat might represent an expulsion mechanism.This publication has 3 references indexed in Scilit:
- Nature of adrenoceptor sites in bovine teat musclesNaunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie, 1977
- RADIOGRAPHIC METHOD FOR ANATOMIC STUDY OF TEAT CANAL - OBSERVATIONS ON 22 LACTATING DAIRY COWS1968
- WALL STRUCTURE AND CLOSING MECHANISMS OF THE BOVINE TEAT1950