A05 Visceral Smooth Muscle

In the following experiments, you will study some of the physiological and pharmacological properties of visceral smooth muscle taken from the rabbit ileum. (The ileum is the last part of the small intestine). You will vary the Ca 2+ concentration, and the temperature and oxygen content of the medium surrounding the muscle. In addition, you will investigate the effects of acetylcholine, atropine, and norepinephrine on the muscle tissue.

You will observe the recordings before and after the various treatments and look for and measure changes in the rhythmicity and in the tonus of the smooth muscle contractions. The Biopac Student Lab PRO will be used to record the contractions.

Experimental Objectives

1. To study the effects of media ionic composition, temperature, and various pharmacological agents on the contraction of the visceral smooth muscle of the rabbit ileum.
2. In particular, the student should be able to:
   1. outline some of the differences between skeletal, cardiac and smooth muscle
   2. distinguish structurally and functionally between two types of smooth muscle, visceral (single-unit) and multi-unit smooth muscle. State where you would expect to find each.
   3. describe excitation-contraction coupling in smooth muscle and compare and contrast it with excitation-contraction coupling in skeletal muscle.
   4. describe the following properties of visceral smooth muscle contraction: tonus, rhythmicity, rate, regularity, and amplitude. Describe how you would identify each of these characteristics in a chart recording.
   5. discuss the importance of calcium in smooth muscle contraction. Describe the effect of removing calcium from the medium on smooth muscle contraction.
   6. describe the effects of oxygen depletion, sustained depolarization and temperature changes on smooth muscle contractions.
   7. describe how an increase in KCl in the extracellular fluid surrounding smooth muscle cells causes depolarization.
   8. describe the effects of norepinephrine, acetylcholine, and atropine on smooth muscle contractions.

Tasks Performed by the Student

After preparing the smooth muscle for testing, the student will record (and compare to baseline) the effects of the following conditions:

• extracellular calcium
• chemical depolarization
• change in temperature
• norepinephrine and Acetylcholine
• atropine
• oxygen depletion

Student Prep & Distance Learning

Click the link(s) below for sample data and/or lesson procedure video(s), BSL PRO Lesson procedures (PDF) for human lessons*, and graph template files (*.gtl) for BSL PRO Lessons. If more than one .gtl is available, download the .gtl with the _suffix to match BSL version and hardware.

• Graph template for BSL PRO Lesson A05
• Click here to request the lesson procedure PDF - animal lessons are available by request only

Lesson Hardware

This lesson requires a Biopac Student Lab (BSL) System and the following hardware. If your BSL System does not include all hardware items, expand your system by selecting required items below. For more details, review the Lesson: L# BSL Lessons - see the Lab Manual or launch BSL; A# and H# BSL PRO Lessons, click the PDF link above to review full setup, recording, and analysis procedures.