https://www.vetsurgeon.org/f/clinical-questions/16259/possible-urethro-spasms-caused-by-atenolol A bit of a poser for any of you with an interest in pharmacology. I have a feline patient on atenolol for cardiac arrhythmia and HCM and it has twice presented with apparent urethral obstruction. When catheterised there has been no physical obstructionen-USTelligent Community 10https://www.vetsurgeon.org/thread/96920?ContentTypeID=1Wed, 04 Sep 2013 10:49:51 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:9791019d-6e9e-477c-b20d-606b5db15f84Martin Atkinson<p>Thanks for that Mark. Also of interest, especially in&nbsp;the&nbsp;light of what you said about beta receptors being&nbsp;important&nbsp;in the storage phase, is that although he is now urinating, he is only half emptying his bladder and initially would allow me to express it very easily&nbsp;conscious although he resisted last time on Monday. It poses another thought that when I&#39;ve done routine examinations on him and felt what I&nbsp;consider&nbsp;a normal half-full bladder, how often has it really been voluntarily half full and how often that he&#39;s just not been able to empty it completely - indeed how could you ever know with any animal?&nbsp;A real question of whether his glass is half empty or half full!</p><div style="clear:both;"></div>https://www.vetsurgeon.org/thread/96919?ContentTypeID=1Wed, 04 Sep 2013 10:38:02 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:e0ec4bc7-4bdc-4a08-8db0-f24f4556d65eMark Lowrie<p><p style="margin:0cm 0cm 10pt;" class="MsoNormal"><span style="font-size:small;font-family:Calibri;">The internal urethral sphincter doesn&rsquo;t contain any beta receptors so I&nbsp;would guess&nbsp;the answer is no. Beta receptors are only found in the detrusor muscle and are important in the storage phase&nbsp;so reversing this trend is unlikely to alter micturition significantly. However, I am not a pharmacologist and am just using first principals. Others may be able to add more.</span></p></p><div style="clear:both;"></div>