Influence of Infratonic Acoustical Frequencies In Vitro on Glioma Cells

Garret Yount and colleagues at the California Pacific Medical Center Research Institute in San Francisco evaluated the potential effects of the Infratonic device on cultured human tumor cells. Garret’s group reported that Infratonic frequency emissions sensitize human glioblastoma cells to the chemotherapeutic agent 5-fluorouracil [Yount et al., 2004, http://www.ncbi.nlm.nih.gov/pubmed/15165405 ]. In a second study Rachlin and colleagues extended these findings by evaluating the potential for Infratonic device emissions to sensitize glioblastoma cells to cisplatin [Rachlin et al., 2012, http://www.ncbi.nlm.nih.gov/pubmed/23165942 ]. The results of this study demonstrate that the Infratonic chemosensitizes U87, U251, SF210, and SF188 glioblastoma cells to cisplatin and that these effects are contributed to in large part by increased membrane permeability.

The potential for infrasound to enhance cellular drug delivery is supported by a small number of studies indicating that exposure can influence cell membrane permeability. Svidovyi and colleagues, for example, studied the effects of infrasound on human erythrocytes in vitro as well as the organs of rats in vivo and reported increased membrane permeability [Svidovyi et al., 1987, 1985, http://www.ncbi.nlm.nih.gov/pubmed/2956159, http://www.ncbi.nlm.nih.gov/pubmed/4085820 ].

The precise mechanisms underlying infrasound-mediated permeabilization are not identified in these studies. Although research on the biological effects of infrasound is limited, relevant studies do exist. A computational analysis of the response of bilayer lipid membranes to pressure waves using molecular dynamics modeling demonstrates that transient permeabilization can be achieved and that membrane thickness and area per lipid are reduced in this instance. http://onlinelibrary.wiley.com/doi/10.1002/fld.1588/pdf .

One early study investigating the responses of artificial bilayer membranes to infrasonic vibrations found that capacitive response decreased with increasing frequency over a narrow range (~0.2 Hz to ~10 Hz)  [http://www.sciencedirect.com/science/article/pii/0021979771900105 ]. Interestingly, the parameters identified in the aforementioned permeability study are also determining factors of membrane capacitance. This supports the notion that cellular membrane permeabilization can be mediated by infrasound and perhaps can even be differentially responsive to specific frequency ranges, and suggests that the alteration of membrane thickness and area per lipid are potential underlying mechanisms.  More research on the biological effects of infrasound will be necessary to evaluate its mechanism of actions in mammalian cells.