An inexpensive system for evaluating the tussive and anti-tussive properties of chemicals in conscious, unrestrained guinea pigs

Introduction: Commercial whole-body plethysmography systems used to evaluate the anti-tussive potential of drugs employ sophisticated technology, but these systems may be cost prohibitive for some laboratories. The present study describes an alternative, inexpensive system for evaluating the tussive and anti-tussive potential of drugs in conscious, unrestrained guinea pigs. Methods: The system is composed of a transparent small animal anesthesia induction box fitted with a microphone, a camera and a pneumotachometer to simultaneously capture audio, video, air flow and air pressure in real time. Data acquisition and analysis was performed using free software for audio and video, and a research pneumotach system for flow and pressure. System suitability testing was performed by exposing conscious, unrestrained guinea pigs to nebulized aqueous solutions of a selective agonist for TRPV1 (citric acid) or a selective agonist for TRPA1 (AITC), with or without pre-treatment with a selective antagonist for TRPV1 (BCTC) or a selective antagonist for TRPA1 (HC-030031). Results: The system easily discerned coughs from other respiratory events like sneezes. System suitability test results are as follows: AITC caused 10.7 (SEM = 1.4592) coughs vs. 5.8 (SEM = 1.6553) when pre-treated with HC-030031 (P < 0.05). Citric acid caused 12.4 (SEM = 1.4697) coughs vs. 3.2 (SEM = 1.3928) when pre-treated with BCTC (P < 0.002). Discussion: We have described in detail an inexpensive system for evaluating the tussive and anti-tussive potential of chemicals in conscious, unrestrained guinea pigs. Suitability testing indicates that the system is comparable to a commercial whole-body plethysmography system for detecting and differentiating between coughs and sneezes. This system may provide some investigators a cost-conscious alternative to more expensive commercial whole-body plethysmography systems.