Effects of extreme potassium stress on blood pressure and renal tubular sodium transport.

We characterized mouse blood pressure and ion transport in the setting of commonly used rodent diets that drive K+ intake to the extremes of deficiency and excess. Male 129S2/Sv mice were fed either K+-deficient, control, high-K+ basic, or high-KCl diets for 10 days. Mice maintained on a K+-deficient diet exhibited no change in blood pressure, whereas K+-loaded mice developed an ~10-mmHg blood pressure increase. Following challenge with NaCl, K+-deficient mice developed a salt-sensitive 8 mmHg increase in blood pressure, whereas blood pressure was unchanged in mice fed high-K+ diets. Notably, 10 days of K+ depletion induced diabetes insipidus and upregulation of phosphorylated NaCl cotransporter, proximal Na+ transporters, and pendrin, likely contributing to the K+-deficient NaCl sensitivity. While the anionic content with high-K+ diets had distinct effects on transporter expression along the nephron, both K+ basic and KCl diets had a similar increase in blood pressure. The blood pressure elevation on high-K+ diets correlated with increased Na+-K+-2Cl- cotransporter and γ-epithelial Na+ channel expression and increased urinary response to furosemide and amiloride. We conclude that the dietary K+ maneuvers used here did not recapitulate the inverse effects of K+ on blood pressure observed in human epidemiological studies. This may be due to the extreme degree of K+ stress, the low-Na+-to-K+ ratio, the duration of treatment, and the development of other coinciding events, such as diabetes insipidus. These factors must be taken into consideration when studying the physiological effects of dietary K+ loading and depletion.

Barriers to Bariatric Surgery: a Mixed Methods Study Investigating Obstacles Between Clinic Contact and Surgery.

PURPOSE: Populations most affected by obesity are not reflected in the patients who undergo bariatric surgery. Gaps in the referral system have been studied, but there is a lack of literature investigating obstacles patients encounter after first contact with bariatric surgery clinics. We aim to identify patient populations at risk for attrition during bariatric surgery evaluation and determine patient reported barriers to bariatric surgical care. MATERIALS AND METHODS: This study was a single institution, retrospective, mixed methods study from 2012 to 2021 comparing patients who underwent bariatric surgery to those that withdrew. Surveys were performed of patients who withdrew, collecting information on patient knowledge, expectations, and barriers. RESULTS: This study included 5982 patients evaluated in bariatric surgery clinic. Those who attained bariatric surgery (38.8%) were more likely to be White (81.2 vs. 75.6%, p<0.001), married (48.5 vs. 44.1%, p=0.004), and employed full time (48.2 vs. 43.8%, p=0.01). They were less likely to live in an area with low income (37.1 vs. 40.7%, p=0.01) or poverty (poverty rate 15.8 vs. 17.4, p<0.001). Of the 280 survey respondents, fear of complications, length of insurance approval process, and wait time between evaluation and surgery were the most reported barriers. CONCLUSION: Patients who undergo bariatric surgery were more likely to be White, married, employed full time, and reside in more resourced environments which is not reflective of communities most affected by obesity. The complexity of insurance coverage requirements was a major barrier to bariatric surgery and should be a focus of future healthcare reform.