Spontaneous activity in isolated bovine mesenteric lymphatics

Longitudinal tension was measured in isolated segments (approximately 20 mm in length and 2 mm in diameter) of bovine mesenteric lymphatic vessels. 2. Seventeen out of thirty‐nine vessels showed regular spontaneous rhythmic contractions, the most common frequency being about 2/min. 3. The strength of each contraction was related to the duration of the preceding pause, a longer pause being associated with a stronger contraction. 4. Noradrenaline increased the frequency and decreased the amplitude of the contractions. This effect was abolished by α‐receptor blockade with phentolamine. 5. Isoprenaline slowed the frequency of the contractions. This effect was abolished by β‐receptor blockade with propranolol. 6. Acetylcholine had little effect on the rate of spontaneous contractions.