On 2017 Apr 16, Md. Shahidul Islam commented:

In the supplementary figure 1 the authors show dramatic (almost 100%) inhibition of glucose- and GLP-1 induced electrical activity and insulin secretion by the TRPM4 inhibitor 9-phenanthrol which they used at a concentration of 50 microM. This could possibly be due to the toxic effect of 9-phenanthrol on the beta cells. It is unclear why the authors needed to use 9-phenanthrol at a concentration of 50 microM (as little as 20 microM would have been enough).

It may be noted that in human beta cells TRPM4 is heavily expressed wheras TRPM5 is almost absent. Pancreas. 2017 Jan;46(1):97-101. Expression of Transient Receptor Potential Channels in the Purified Human Pancreatic β-Cells. Marabita F1, Islam MS. PMID: 27464700 DOI: 10.1097/MPA.0000000000000685

On 2017 Apr 16, Md. Shahidul Islam commented:

In the supplementary figure 1 the authors show dramatic (almost 100%) inhibition of glucose- and GLP-1 induced electrical activity and insulin secretion by the TRPM4 inhibitor 9-phenanthrol which they used at a concentration of 50 microM. This could possibly be due to the toxic effect of 9-phenanthrol on the beta cells. It is unclear why the authors needed to use 9-phenanthrol at a concentration of 50 microM (as little as 20 microM would have been enough).

It may be noted that in human beta cells TRPM4 is heavily expressed wheras TRPM5 is almost absent. Pancreas. 2017 Jan;46(1):97-101. Expression of Transient Receptor Potential Channels in the Purified Human Pancreatic β-Cells. Marabita F1, Islam MS. PMID: 27464700 DOI: 10.1097/MPA.0000000000000685