Effects of Drugs on Pulsation Rate of Lumbriculus variegatus (Blackworms)

Overview

• Purpose: To study the effect of drugs on the pulsation rate of the blackworm's circulatory system.
• Organism: Lumbriculus variegatus, a freshwater oligochaete worm.
• Applications: Useful for studying the circulatory system, homeostasis, behavior, toxicology, and the nervous system.

Blackworm Characteristics

• Features:
  • Transparent skin allows easy observation of the circulatory system.
  • Quick drug diffusion through skin for immediate effects.
  • Easy laboratory maintenance.
• Circulatory System:
  • Dorsal blood vessel pumps blood using muscular contractions.
  • Pulsation rate is regulated by the nervous and endocrine systems.

Lab Exercise Structure

• Part I: Handling procedures and initial observations of blackworm behavior and pulsation rate.
• Part II: Student-designed experiments to test drug effects on pulsation rate.
• Skills Developed:
  • Scientific inquiry and critical thinking.
  • Data collection and analysis.
  • Collaborative work.
  • Written and oral presentation skills.

Lab Objectives

1. Identify blackworms.
2. Explain the circulatory system and functions.
3. Measure pulsation frequency and velocity.
4. Understand drug effects on the circulatory system.
5. Design and implement experiments.
6. Present results.

Lab Procedure

• Preparation:
  • Start culturing worms 2-4 weeks in advance.
  • Prepare solutions 24 hours in advance.
• In-lab Timing:
  • Introduction (10 mins)
  • Worm handling (15 mins)
  • Baseline rate determination (30 mins)
  • Experiment design (20 mins)
  • Running experiment (45 mins)

Experimental Design

• Dependent Variable: Pulsation rate of blackworms.
• Independent Variables: Type of drug, concentration, exposure time.
• Control: Untreated worms.

Results and Observations

• Data Collection:
  • Use tables and graphs to present pulsation rates.
  • Compare with baseline data.
• Conclusion:
  • Hypothesis testing.
  • Analyze data to support or refute hypotheses.
  • Suggestions for improved experimental design.

Drug Effects on Pulsation Rate

• Nicotine: Increases pulsation rate by mimicking neurotransmitters.
• Caffeine: Increases pulsation rate; mechanism in blackworms unclear.
• Alcohol: Decreases pulsation rate by blocking ion channels.

Safety and Precautions

• Handle organisms and microscopes with care.
• Use gloves with hazardous chemicals.
• Proper disposal of chemicals.
• Report any injuries to the TA.

Instructor Notes

• Ensure students have prerequisite knowledge.
• Encourage formulation of specific, testable hypotheses.
• Guide students through experimental procedure.
• Have data for control group prepared.

Additional Resources

• Visit Dr. C. Drewes' website for more information on blackworms and lab activities.

Acknowledgements

• Dedicated to Dr. Charles Drewes for his contributions to blackworm research and education.

References

• Drewes, CD. (2003, 2001, 1996)
• Lesiuk, NM and Drewes, CD. (1999)